[pkg-go] Bug#831724: mtail: FTBFS on non-amd64: go test -race unsupported

[Aaron M. Ucko]

Package: mtail
Version: 0.0+git20160704.35c4023-1
Severity: important
Justification: fails to build from source

Builds of mtail for architectures other than amd64 all failed:

  GOPATH=/«BUILDDIR»/mtail-0.0+git20160704.35c4023/build go test -v -timeout 5m -race github.com/google/mtail
  go test: -race and -msan are only supported on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64
  debian/rules:25: recipe for target 'override_dh_auto_test' failed
  make[1]: *** [override_dh_auto_test] Error 2
  make[1]: Leaving directory '/«BUILDDIR»/mtail-0.0+git20160704.35c4023'
  debian/rules:17: recipe for target 'build-arch' failed
  make: *** [build-arch] Error 2

Could you please arrange to skip this test for these architectures?

Thanks!