x/mobile: Cannot handle javap error message with non-English environment

[tenntenn]

Please answer these questions before submitting your issue. Thanks!

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

go version go1.7.3 darwin/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/tenntenn/Documents/gopath"
GORACE=""
GOROOT="/usr/local/go1.7"
GOTOOLDIR="/usr/local/go1.7/pkg/tool/darwin_amd64"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/mq/m9_twy8j1vl9ppr6j5xqtfq80000gn/T/go-build135510012=/tmp/go-build -gno-record-gcc-switches -fno-common"
CXX="clang++"
CGO_ENABLED="1"

What did you do?

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

With my Japanese environment, javap report errors in Japanese.

$ /usr/bin/javap -s -protected -constants com.example.ExampleClass
エラー: クラスが見つかりません: com.example.ExampleClass

But java.Importer.Import handles errors using javap's output in English.
So javap should be called with -J-Duser.language=en option.

What did you expect to see?

Successfully build.

What did you see instead?

Build error.

[gopherbot]

CL https://golang.org/cl/33371 mentions this issue.