cmd/cgo: TestCgoExternalThreadPanic fails by "invalid relocation and dwarf: definition of unknown kind 0" on openbsd/386

[mikioh]

See https://storage.googleapis.com/go-build-log/9460f554/openbsd-386-gce56_6fb4d378.log

##### GOMAXPROCS=2 runtime -cpu=1,2,4
--- FAIL: TestCgoExternalThreadPanic (1.53s)
    crash_test.go:92: building source: exit status 2
        # _/tmp/go-build410912323
        type.*struct { F uintptr; s **runtime.mspan; h *runtime.mheap; npage uintptr; sizeclass int32; large bool }: type.*struct { F uintptr; s **runtime.mspan; h *runtime.mheap; npage uintptr; sizeclass int32; large bool }: invalid relocation 0+173 not in [0,44)
        syscall.errors: dwarf: definition of unknown kind 0: type.*struct { F uintptr; s **runtime.mspan; h *runtime.mheap; npage uintptr; sizeclass int32; large bool }
FAIL
FAIL    runtime 53.702s

[bradfitz]

Just saw another on openbsd-386 at 4a8dbaa (but passed before & after):

http://build.golang.org/log/087d2ce773bc58aa635485cb32750acd996ecc28

##### GOMAXPROCS=2 runtime -cpu=1,2,4
--- FAIL: TestCgoExternalThreadPanic-2 (1.36s)
    crash_test.go:92: building source: exit status 2
        # _/tmp/go-build428181342
        type..alg524288: type..alg524288: invalid relocation 414911616+173 not in [0,8)
        type..alg524288: missing xsym in relocation
        type..alg524288: missing xsym in relocation
        panic: runtime error: invalid memory address or nil pointer dereference
        [signal 0xb code=0x1 addr=0x1eb pc=0x80e41e2]

        goroutine 1 [running]:
        cmd/internal/ld.undefsym(0x1877c000)
            /tmp/buildlet-scatch752582679/go/src/cmd/internal/ld/lib.go:1791 +0x92
        cmd/internal/ld.undef()
            /tmp/buildlet-scatch752582679/go/src/cmd/internal/ld/lib.go:1805 +0x56
        cmd/internal/ld.Ldmain()
            /tmp/buildlet-scatch752582679/go/src/cmd/internal/ld/pobj.go:241 +0x1828
        main.main()
            /tmp/buildlet-scatch752582679/go/src/cmd/8l/obj.go:44 +0x1d
FAIL

I'm going to tag this Go 1.5 until we at least understand it. If it ends up being an OpenBSD-specific thing, we wouldn't hold up the release for it.

[rsc]

Given the lack of activity, I assume this has resolved itself or is openbsd-specific. If the issue should be reopened, please remove the Go1.5 milestone.