mosys: Add an option to specify a location for cros_config_data.c

The ebuild currently copies the file from the sysroot into the source
directory. Lets stop doing that since the work dir just contains a
symlink to the source.

I will have a followup that will change the ebuild.

BUG=none
TEST=Build mosys with and without the flag.

Change-Id: I98db5d63326123fbf27418ff51e81f0502f8fa98
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1625454
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Yuval Peress <peress@chromium.org>
3 files changed