Race Condition Detection disabled when run in Docker (until Go 1.15)

[ThomasObenaus]

With current alpine (golang:1.13.1-alpine) test -race does not work since it is not supported.

--> Run the unit-tests
# runtime/race
/usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: race_linux_amd64.syso: in function `__sanitizer::GetArgv()':
gotsan.cc:(.text+0x4183): undefined reference to `__libc_stack_end'
/usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: race_linux_amd64.syso: in function `__sanitizer::ReExec()':
gotsan.cc:(.text+0x9797): undefined reference to `__libc_stack_end'
/usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: race_linux_amd64.syso: in function `__sanitizer::InternalAlloc(unsigned long, __sanitizer::SizeClassAllocatorLocalCache<__sanitizer::SizeClassAllocator32<__sanitizer::AP32> >*, unsigned long)':
gotsan.cc:(.text+0xaac1): undefined reference to `__libc_malloc'
/usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: race_linux_amd64.syso: in function `__sanitizer::InternalRealloc(void*, unsigned long, __sanitizer::SizeClassAllocatorLocalCache<__sanitizer::SizeClassAllocator32<__sanitizer::AP32> >*)':
gotsan.cc:(.text+0xca20): undefined reference to `__libc_realloc'
/usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: race_linux_amd64.syso: in function `__sanitizer::InternalFree(void*, __sanitizer::SizeClassAllocatorLocalCache<__sanitizer::SizeClassAllocator32<__sanitizer::AP32> >*)':
gotsan.cc:(.text+0x66e8): undefined reference to `__libc_free'
collect2: error: ld returned 1 exit status

As mentioned here golang/go#14481 (comment) with go 1.15. + the according alpine image the issue will be resolved.
Hence then it can be renabled.