clang:try Ofast in replacement with O3, also enabled munaligned-access and ensured vectorization is enabled

This might cause instability because Ofast enables ffast-math that may break floating point standard

Change-Id: Iaf012c9396fea51c6d3eda50695c4479de3eb712
Merge remote-tracking branch 'cyanogen/cm-12.0' into HEAD