If recovery_resources_extra doesn't exist, do not define, in order to
avoid "find bootable/recovery*/res-720 'no such file or directory' in
during `make` use. Ex: make clobber

Change-Id: I8ac434c3889c0a61a28d6c137581c7390fa21643
My goto-dir ONLY FLAGS

Change-Id: I3ed147f180267db975ee556a4730c2c1dad2d554