cmd/link: regression in handling of linker flags

[dsnet]

Commit fa8a28d introduced a regression where -ldflags doesn't quite work like it used to.

Reproduction:

$ GO_LDFLAGS='-I /lib/x86_64-linux-gnu/ld-linux-x86-64.so.2' ./make.bash

# cmd/go
/home/rawr/Projects/go/pkg/tool/linux_amd64/link: conflict dynlinker: /lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 and /lib64/ld-linux-x86-64.so.2
runtime/cgo(.text): stderr: not defined
runtime/cgo(.text): fwrite: not defined
runtime/cgo(.text): __vfprintf_chk: not defined
runtime/cgo(.text): fputc: not defined
runtime/cgo(.text): abort: not defined
runtime/cgo(.text): pthread_create: not defined
runtime/cgo(.text): strerror: not defined
runtime/cgo(.text): stderr: not defined
runtime/cgo(.text): __fprintf_chk: not defined
runtime/cgo(.text): abort: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_cond_wait: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_cond_broadcast: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
/home/rawr/Projects/go/pkg/tool/linux_amd64/link: too many errors

##### Building Go bootstrap tool.
cmd/dist

##### Building Go toolchain using /usr/local/go1.4.3.
bootstrap/internal/dwarf
bootstrap/internal/sys
bootstrap/asm/internal/flags
bootstrap/internal/bio
bootstrap/compile/internal/big
bootstrap/internal/obj
bootstrap/compile/internal/syntax
bootstrap/internal/gcprog
bootstrap/internal/obj/arm
bootstrap/internal/obj/arm64
bootstrap/internal/obj/mips
bootstrap/internal/obj/ppc64
bootstrap/internal/obj/s390x
bootstrap/internal/obj/x86
bootstrap/asm/internal/lex
bootstrap/link/internal/ld
bootstrap/compile/internal/ssa
bootstrap/asm/internal/arch
bootstrap/asm/internal/asm
bootstrap/asm
bootstrap/link/internal/amd64
bootstrap/link/internal/arm
bootstrap/link/internal/arm64
bootstrap/link/internal/mips64
bootstrap/link/internal/ppc64
bootstrap/link/internal/s390x
bootstrap/link/internal/x86
bootstrap/link
bootstrap/compile/internal/gc
bootstrap/compile/internal/amd64
bootstrap/compile/internal/arm
bootstrap/compile/internal/arm64
bootstrap/compile/internal/mips64
bootstrap/compile/internal/ppc64
bootstrap/compile/internal/s390x
bootstrap/compile/internal/x86
bootstrap/compile

##### Building go_bootstrap for host, linux/amd64.
runtime/internal/sys
runtime/internal/atomic
runtime
encoding
errors
internal/race
internal/syscall/windows/sysdll
math
sort
sync/atomic
unicode
unicode/utf16
unicode/utf8
sync
container/heap
internal/singleflight
io
syscall
bytes
hash
strings
strconv
hash/adler32
bufio
reflect
encoding/base64
crypto
path
regexp/syntax
crypto/sha1
internal/syscall/windows
internal/syscall/windows/registry
time
regexp
os
os/signal
path/filepath
io/ioutil
encoding/binary
fmt
context
flag
go/token
log
net/url
text/template/parse
compress/flate
encoding/json
debug/dwarf
go/scanner
os/exec
go/ast
debug/macho
compress/zlib
debug/elf
text/template
go/parser
go/doc
go/build
cmd/go

##### Building packages and commands for linux/amd64.
runtime/internal/sys
runtime/internal/atomic
runtime
errors
internal/race
sync/atomic
unicode
unicode/utf8
math
sort
sync
container/heap
container/list
io
syscall
container/ring
crypto/subtle
bytes
strings
path
bufio
hash
hash/adler32
text/tabwriter
hash/crc32
compress/bzip2
strconv
crypto/cipher
time
math/rand
crypto/hmac
internal/syscall/unix
internal/nettrace
internal/singleflight
encoding
unicode/utf16
vendor/golang_org/x/net/lex/httplex
hash/crc64
reflect
regexp/syntax
crypto
crypto/aes
os
crypto/sha512
path/filepath
crypto/md5
crypto/rc4
regexp
crypto/sha1
io/ioutil
crypto/sha256
encoding/base64
encoding/pem
encoding/ascii85
encoding/base32
hash/fnv
html
image/color
internal/syscall/windows/sysdll
runtime/debug
runtime/trace
image
image/color/palette
math/cmplx
os/signal
runtime/race
cmd/compile/internal/test
cmd/internal/pprof/svg
cmd/vet/internal/whitelist
fmt
encoding/binary
image/internal/imageutil
image/draw
image/jpeg
cmd/internal/sys
crypto/des
index/suffixarray
cmd/internal/dwarf
log
flag
debug/dwarf
compress/flate
debug/gosym
debug/plan9obj
cmd/internal/obj
cmd/vendor/golang.org/x/arch/arm/armasm
compress/zlib
debug/macho
debug/pe
debug/elf
cmd/vendor/golang.org/x/arch/x86/x86asm
archive/tar
cmd/internal/goobj
archive/zip
compress/gzip
compress/lzw
context
cmd/internal/objfile
math/big
encoding/hex
go/token
os/exec
cmd/addr2line
go/scanner
go/ast
database/sql/driver
encoding/csv
encoding/gob
database/sql
crypto/dsa
crypto/elliptic
encoding/asn1
crypto/rand
go/parser
crypto/rsa
go/printer
crypto/ecdsa
crypto/x509/pkix
encoding/json
encoding/xml
vendor/golang_org/x/net/http2/hpack
mime
mime/quotedprintable
cmd/cgo
net/http/internal
net/url
text/template/parse
go/constant
go/format
text/scanner
image/gif
go/types
image/png
text/template
runtime/pprof
testing
runtime/cgo
go/doc
html/template
go/build
internal/testenv
internal/trace
net/internal/socktest
net
os/user
testing/iotest
testing/quick
cmd/internal/obj/arm
go/internal/gccgoimporter
go/internal/gcimporter
go/importer
cmd/api
cmd/internal/obj/arm64
cmd/internal/obj/mips
cmd/internal/obj/ppc64
cmd/internal/obj/s390x
cmd/internal/obj/x86
cmd/asm/internal/flags
cmd/asm/internal/lex
cmd/internal/bio
cmd/compile/internal/big
cmd/compile/internal/ssa
crypto/x509
net/textproto
mime/multipart
crypto/tls
net/http/httptrace
log/syslog
net/mail
cmd/asm/internal/arch
cmd/compile/internal/syntax
cmd/asm/internal/asm
cmd/asm
net/http
net/smtp
cmd/internal/gcprog
cmd/cover
cmd/dist
cmd/doc
cmd/fix
cmd/gofmt
cmd/internal/pprof/profile
cmd/internal/pprof/tempfile
cmd/link/internal/ld
cmd/internal/pprof/plugin
cmd/internal/pprof/report
expvar
net/http/cgi
net/http/cookiejar
net/http/fcgi
net/http/httptest
net/http/httputil
net/http/pprof
net/rpc
cmd/go
net/rpc/jsonrpc
cmd/internal/pprof/commands
cmd/internal/pprof/driver
cmd/internal/pprof/fetch
cmd/internal/pprof/symbolizer
cmd/internal/pprof/symbolz
cmd/link/internal/amd64
cmd/link/internal/arm
cmd/link/internal/arm64
cmd/link/internal/mips64
cmd/link/internal/ppc64
cmd/link/internal/s390x
cmd/link/internal/x86
cmd/nm
cmd/link
cmd/objdump
cmd/pack
cmd/pprof
# cmd/go
/home/rawr/Projects/go/pkg/tool/linux_amd64/link: conflict dynlinker: /lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 and /lib64/ld-linux-x86-64.so.2
runtime/cgo(.text): stderr: not defined
runtime/cgo(.text): fwrite: not defined
runtime/cgo(.text): __vfprintf_chk: not defined
runtime/cgo(.text): fputc: not defined
runtime/cgo(.text): abort: not defined
runtime/cgo(.text): pthread_create: not defined
runtime/cgo(.text): strerror: not defined
runtime/cgo(.text): stderr: not defined
runtime/cgo(.text): __fprintf_chk: not defined
runtime/cgo(.text): abort: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_cond_wait: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_cond_broadcast: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
/home/rawr/Projects/go/pkg/tool/linux_amd64/link: too many errors
cmd/trace
cmd/vet/internal/cfg
cmd/vet
# cmd/pprof
/home/rawr/Projects/go/pkg/tool/linux_amd64/link: conflict dynlinker: /lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 and /lib64/ld-linux-x86-64.so.2
runtime/cgo(.text): stderr: not defined
runtime/cgo(.text): fwrite: not defined
runtime/cgo(.text): __vfprintf_chk: not defined
runtime/cgo(.text): fputc: not defined
runtime/cgo(.text): abort: not defined
runtime/cgo(.text): pthread_create: not defined
runtime/cgo(.text): strerror: not defined
runtime/cgo(.text): stderr: not defined
runtime/cgo(.text): __fprintf_chk: not defined
runtime/cgo(.text): abort: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_cond_wait: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_cond_broadcast: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
/home/rawr/Projects/go/pkg/tool/linux_amd64/link: too many errors
# cmd/trace
/home/rawr/Projects/go/pkg/tool/linux_amd64/link: conflict dynlinker: /lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 and /lib64/ld-linux-x86-64.so.2
runtime/cgo(.text): stderr: not defined
runtime/cgo(.text): fwrite: not defined
runtime/cgo(.text): __vfprintf_chk: not defined
runtime/cgo(.text): fputc: not defined
runtime/cgo(.text): abort: not defined
runtime/cgo(.text): pthread_create: not defined
runtime/cgo(.text): strerror: not defined
runtime/cgo(.text): stderr: not defined
runtime/cgo(.text): __fprintf_chk: not defined
runtime/cgo(.text): abort: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_cond_wait: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_cond_broadcast: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
runtime/cgo(.text): pthread_mutex_lock: not defined
runtime/cgo(.text): pthread_mutex_unlock: not defined
/home/rawr/Projects/go/pkg/tool/linux_amd64/link: too many errors
cmd/compile/internal/gc
cmd/compile/internal/amd64
cmd/compile/internal/arm
cmd/compile/internal/mips64
cmd/compile/internal/arm64
cmd/compile/internal/ppc64
cmd/compile/internal/s390x
cmd/compile/internal/x86
cmd/compile

/cc @matloob @crawshaw

[matloob]

I believe this was fixed by golang.org/cl/27562. Please assign back to me if that is not the case.

[dsnet]

I confirm that this is fixed.