subdirs = ["bionic/*"] in the root Blueprints causes blueprint to
search subdirectories of bionic for Blueprints files instead of
searching the bionic directory itself. Replace it with
subdirs = ["bionic"] and allow bionic/Blueprints to specify its
subdirs.
Change-Id: Iac9d2407a3d4c87b3c23390f887b187f276ee72f