Support systems that use a full copy of recovery image.

If BOARD_USES_FULL_RECOVERY_IMAGE == true, a full copy of recovery
image will be carried as /system/etc/recovery.img instead of a patch
at /system/recovery_from_boot.p.

Bug: 22641135
Change-Id: Ie271d3e2d55d7b003f667ac5b44203d69b23c63b
(cherry picked from commit 8beab69b)