Rename "Makefile" to "Android.mk" throughout the tree.

For <http://b/issue?id=960416

>.

I've tested this as much as I can, but 1500 open files =
easy to mess things up.  Please let me know if there's
a problem rather than rolling back this change.

PRESUBMIT=passed
BUG=960416
TBR=joeo
OCL=46537

Change-Id: I5a404caf0f398a7afa7ae7abaf2f2a1c6ab490eb
Signed-off-by: Glenn Kasten <gkasten@google.com>