This CL adds the real cmd/internal/obj packages.
Collectively they correspond to the liblink library.
The conversion was done using rsc.io/c2go's run script
at rsc.io/c2go repo version 706fac7.

This is not the final conversion, just the first working draft.
There will be more updates, but this works well enough
to use with go tool objwriter and pass all.bash.

Change-Id: I9359e835425f995a392bb2fcdbebf29511477bed
Reviewed-on: https://go-review.googlesource.com/3046Reviewed-by: Ian Lance Taylor <iant@golang.org>