fix up ota_from_target_files symlink detection.
add adb to the disttools

Change-Id: I898fa5c9396606144e57dba8453f476b9e9440ab
ro.secure=0
enable_target_debugging := true
WITH_DEXPREOPT := false
build: Drop applypatch from stock recovery
credits: @rascarlo
ota release tools: override device assert

Conflicts:
	tools/releasetools/ota_from_target_files
fix BUILD_PROP_OVERRIDES
Remove --block
Backup tool support