Overlay support for legacy camera libs

Move http://review.cyanogenmod.com/#/c/13285/ to proper place for jellybean.

1. Rename OverlayHtc to Overlay in file names
2. Use BOARD_USES_LEGACY_OVERLAY to enable

Signed-off-by: Evan McClain <aeroevan@gmail.com>
Change-Id: I705bc802c7280eda273e881612165c5d3c30ea26