libhwc: Lower optimization level
gralloc: Fix some differences with compatibility code

Summary:
Change-Id: I0f41ff987b6b3f554e11ea2f259d778c8cee7fa2

Merge remote-tracking branch 'cm/cm-10.2' into merge_cm

Test Plan: UNTESTED!, interested parties test and merge

Reviewers: synergy

Reviewed By: synergy

Differential Revision: http://review.codefirex.com/D519