go: x/mobile: gomobile bind does not work with cgo and android

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

go version go1.13.4 darwin/amd64

Does this issue reproduce with the latest release?

Yes

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

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/anjmao/Library/Caches/go-build"
GOENV="/Users/anjmao/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/anjmao/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/p8/5ggx21z124n8kxx2wfv674380000gp/T/go-build165303278=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I have this simple test package with cgo and I’m building it for android with android-ndk-r20.

package test

// #include <stdlib.h>
import "C"

type cCharPointer struct {
	Ptr *C.char
}

func Hello() string {
	return "hi"
}

Build:

gomobile bind -o App.aar -target=android $GOPATH/mobile/test

What did you expect to see?

No error. Note that:

1. It works if I specify ios target.
2. It works for both android and ios if cgo is not used.
3. It works with cgo for older gomobile version. Tested with this commit

What did you see instead?

Error:

gomobile: /Users/anjmao/go/bin/gobind -lang=go,java -outdir=/var/folders/p8/5ggx21z124n8kxx2wfv674380000gp/T/gomobile-work-476890504 github.com/mobile/test failed: exit status 1
[/Users/anjmao/go/src/github.com/mobile/test/test.go:4:8: could not import C (no metadata for C)]