Bug: 5153694
To build cache.img, set BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE (required,
ext4 only for now), BOARD_CACHEIMAGE_PARTITION_SIZE (optional) in
BoardConfig.mk.
Change-Id: I1d8b91646aa1dba88285e008ad3335768bcbddd2
Bug: 5398808
Before this change we have duplicate code in the Makefile and the
python-based releasetool. That's a real headache to maintain.
Change-Id: I8ddf04a79c6886540e89d990f723d8f77c9dd883