fix up ota_from_target_files symlink detection.

Change-Id: I3ede1d1a6628a275adee117b3b9831d9ca831470
Note that update-api is a lie.

Change-Id: Idc2d92630e94ccbd60b5d5447c3762db8e5096f8
add adb to the disttools

Change-Id: I898fa5c9396606144e57dba8453f476b9e9440ab
add make bacon and custom releasetool

also:
  add backuptool items + fixes
  remove duplicate "OPTIONS.worker_threads"
  ota_from_target_files: more derps

Change-Id: I4f61b6a6b9b8bab8582fa5423c4134c07af17606

Conflicts:
	core/Makefile