Build - Add a unique build number to every build

SDK-readable via android.os.Build.INCREMENTAL

Fix exporting the unique build identifier

Fix incremental build number on Darwin

Darwin does not include sha1sum, but it should have openssl.

Use openssl instead of sha1sum

Change-Id: I60864cfeb79830d5686826fc2c02f1ee1bb7a32f
Signed-off-by: STELIX <ssspinni@gmail.com>
Build - Don't run backuptool on GMS builds

Change-Id: Ied688d8f4604d8e4cae34955b79d8a423d3200ea
Signed-off-by: STELIX <ssspinni@gmail.com>