liblight: Add battery light support

Change-Id: I4b73363545b71fbb435b9b577fdfff30d756b90c

Conflicts:
	overlay/frameworks/base/core/res/res/values/config.xml

Conflicts:
	overlay/frameworks/base/core/res/res/values/config.xml
hammerhead: Suppress secure erase

Use the hack to speed up flashing (by the factor of 10).

Change-Id: I921bba5561bcca23fd94c9ada4d1e433389fb6e9

Conflicts:
	BoardConfig.mk
hammerhead: Always keep 3 buffers ready

 * Reduces overall jank system-wide

Change-Id: I37f6021237c81197063d3fd1fd7e5e07626490c9
hammerhead: Better mount options to improve performance

Change-Id: I18f7165c2ff8547b7968d946336d948fe30522b1
Remove the extra we did not need