Created by: linzhp
A generated Go package that include Go, Cgo, C and header files can be built with Go toolchain. This PR makes it possible to build with Buck too. The detail of the scenario can be found in the added test.
@styurin @mkaczanowski Please take a look. Or let me know if you found Buck is already able to build the package generated by :gen target in the testdata of this PR, without the code changes in this PR.