Introduce options -javapkg and -prefix for gobind command.
The following generates java class Testpkg with package name com.example.
gobind -lang=java -javapkg=com.example testpkg
The following generates objective-c files where function and type names
are prefixed with ExampleTestpkg.
gobind -lang=objc -prefix=Example testpkg
As discussed in golang/go#9660 and golang/go#12245.
Gomobile support is not yet implemented.
Change-Id: Ib9e39997ce915580a5a2e25643c0c28373f27ee1
Reviewed-on: https://go-review.googlesource.com/13969
Reviewed-by: David Crawshaw <crawshaw@golang.org>