gcc/gcc-source: Move libcc1 manipulation into gcc-source

gcc/gcc-source: Move libcc1 manipulation into gcc-source

Currently there is a race where if you build -cross-canadian without building gcc (target)
you see QA errors about RPATHS. I've tracked this down to this manipulation where the
target gcc recipe changes libcc1 in the shared sources directory. As long as you build
things in the right order, the problem doesn't occur.

Since its changing ${S} move it to gcc-source and avoid the race, saving RP
some head scratching about why unrelated changes failed to build cleanly.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>