cmd: allow buildmode=c-shared for android/386

Update golang/go#9327.

Change-Id: Iab7dad31cf6b9f9347c3f34faebb67ecb38b17fc
Reviewed-on: https://go-review.googlesource.com/16701
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/cmd/dist/test.go

@@ -616,7 +616,9 @@ func (t *tester) supportedBuildmode(mode string) bool {
 		return false
 	case "c-shared":
 		switch pair {
-		case "linux-386", "linux-amd64", "darwin-amd64", "android-arm", "linux-arm", "linux-arm64":
+		case "linux-386", "linux-amd64", "linux-arm", "linux-arm64",
+			"darwin-amd64",
+			"android-arm", "android-386":
 			return true
 		}
 		return false

src/cmd/go/build.go

@@ -351,7 +351,7 @@ func buildModeInit() {
 		} else {
 			switch platform {
 			case "linux/amd64", "linux/arm", "linux/arm64", "linux/386",
-				"android/amd64", "android/arm":
+				"android/amd64", "android/arm", "android/386":
 				codegenArg = "-shared"
 			case "darwin/amd64":
 			default:

src/cmd/link/internal/ld/lib.go

@@ -325,7 +325,14 @@ func (mode *BuildMode) Set(s string) error {
 		}
 		*mode = BuildmodeCShared
 	case "shared":
-		if goos != "linux" || (goarch != "386" && goarch != "amd64" && goarch != "arm" && goarch != "arm64" && goarch != "ppc64le") {
+		switch goos {
+		case "linux":
+			switch goarch {
+			case "386", "amd64", "arm", "arm64", "ppc64le":
+			default:
+				return badmode()
+			}
+		default:
 			return badmode()
 		}
 		*mode = BuildmodeShared