build: Ensure /system unmounted at install start

Account for the possibility that a user has mounted system manually
before installing the FullOTA package.

Change-Id: I97d0540676a7ce98762545e76ecb1a7f6335d204
repopick: handle variant hal branching

Change-Id: Ib0dee19abc13a7fb8d8e42c09b73c1b4f35ca938
releasetools: ota_from_target_files: add FullOTA_PostValidate

Change-Id: I152412049f90fd546d4516cc064238c3192be553
Add ext2, ext3, and vfat to releasetools

Support some non-standard partition that may be found in recovery.fstab

Conflicts:
	tools/releasetools/common.py

Change-Id: I0026a1d3ae5d432db10150d1a15f7bc8e7a6054b
core: Enable -mcpu=cortex-a8 flag for Scorpion cpu variant

To be used with
	http://review.cyanogenmod.org/#/c/77758/

Change-Id: I7ecc4707fa45bd7098165615c0521a12c85fb087