x/mobile: universe.objc.h file copy fails on case-sensitive system

[tadovas]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.11 linux/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build230554153=/tmp/go-build -gno-record-gcc-switches"

What did you do?

gomobile bind -x -v -work --target=ios/arm64

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

What did you expect to see?

Successful gomobile bind on linux

What did you see instead?

gomobile bind tries to copy universe.objc.h file (instead of generated Universe.objc.h).
cp $WORK/src/gobind/universe.objc.h mobile.framework/Versions/A/Headers/universe.objc.h
This works on darwin (somehow), but obviously fails on linux machines (because of upper/lower case mismatch.
It's a single line fix. PR is coming

[gopherbot]

Change https://golang.org/cl/144117 mentions this issue: gomobile: Start universe filename uppercase