cmd/gomobile: disable DWARF in gomobile builds

DWARF doesn't work for buildmode exe binaries; see
golang.org/issues/25148.

Fixes golang/go#25148.

Change-Id: I511599f3d1963ff0b3e48ac5c8cce50ee6aa54de
Reviewed-on: https://go-review.googlesource.com/110059
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/cmd/gomobile/build_darwin_test.go b/cmd/gomobile/build_darwin_test.go
index ec39119..3b33832 100644
--- a/cmd/gomobile/build_darwin_test.go
+++ b/cmd/gomobile/build_darwin_test.go
@@ -76,10 +76,10 @@
 echo "{{template "infoplist" .Xinfo}}" > $WORK/main/Info.plist
 mkdir -p $WORK/main/Images.xcassets/AppIcon.appiconset
 echo "{{.Xcontents}}" > $WORK/main/Images.xcassets/AppIcon.appiconset/Contents.json
-GOARM=7 GOOS=darwin GOARCH=arm CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch armv7 CGO_LDFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch armv7 CGO_ENABLED=1 go build -tags tag1 ios -x -o=$WORK/arm golang.org/x/mobile/example/basic
-GOOS=darwin GOARCH=arm64 CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch arm64 CGO_LDFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch arm64 CGO_ENABLED=1 go build -tags tag1 ios -x -o=$WORK/arm64 golang.org/x/mobile/example/basic
-GOOS=darwin GOARCH=386 CC=clang-iphonesimulator CXX=clang-iphonesimulator CGO_CFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch i386 CGO_LDFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch i386 CGO_ENABLED=1 go build -tags tag1 ios -x -o=$WORK/386 golang.org/x/mobile/example/basic
-GOOS=darwin GOARCH=amd64 CC=clang-iphonesimulator CXX=clang-iphonesimulator CGO_CFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch x86_64 CGO_LDFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch x86_64 CGO_ENABLED=1 go build -tags tag1 ios -x -o=$WORK/amd64 golang.org/x/mobile/example/basic
+GOARM=7 GOOS=darwin GOARCH=arm CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch armv7 CGO_LDFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch armv7 CGO_ENABLED=1 go build -tags tag1 ios -x -ldflags=-w -o=$WORK/arm golang.org/x/mobile/example/basic
+GOOS=darwin GOARCH=arm64 CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch arm64 CGO_LDFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch arm64 CGO_ENABLED=1 go build -tags tag1 ios -x -ldflags=-w -o=$WORK/arm64 golang.org/x/mobile/example/basic
+GOOS=darwin GOARCH=386 CC=clang-iphonesimulator CXX=clang-iphonesimulator CGO_CFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch i386 CGO_LDFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch i386 CGO_ENABLED=1 go build -tags tag1 ios -x -ldflags=-w -o=$WORK/386 golang.org/x/mobile/example/basic
+GOOS=darwin GOARCH=amd64 CC=clang-iphonesimulator CXX=clang-iphonesimulator CGO_CFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch x86_64 CGO_LDFLAGS=-isysroot=iphonesimulator -mios-simulator-version-min=6.1 -arch x86_64 CGO_ENABLED=1 go build -tags tag1 ios -x -ldflags=-w -o=$WORK/amd64 golang.org/x/mobile/example/basic
 xcrun lipo -o $WORK/main/main -create $WORK/arm $WORK/arm64 $WORK/386 $WORK/amd64
 mkdir -p $WORK/main/assets
 xcrun xcodebuild -configuration Release -project $WORK/main.xcodeproj -allowProvisioningUpdates DEVELOPMENT_TEAM={{.TeamID}}
diff --git a/cmd/gomobile/build_iosapp.go b/cmd/gomobile/build_iosapp.go
index 67455f9..0b0ff2c 100644
--- a/cmd/gomobile/build_iosapp.go
+++ b/cmd/gomobile/build_iosapp.go
@@ -73,7 +73,8 @@
 	var nmpkgs map[string]bool
 	for _, arch := range archs {
 		path := filepath.Join(tmpdir, arch)
-		if err := goBuild(src, darwinEnv[arch], "-o="+path); err != nil {
+		// Disable DWARF; see golang.org/issues/25148.
+		if err := goBuild(src, darwinEnv[arch], "-ldflags=-w", "-o="+path); err != nil {
 			return nil, err
 		}
 		if nmpkgs == nil {