C++11: turn off error warning for only the error we want to turn off

previously was setting -Wno-error to get arround C++11 narrowing violations

Change-Id: I620b1d524bce4642f3f0b4af446e00394177e42b

Conflicts:
	Android.mk
CLANG: Workaround for violations on unsupported command -mtune=cortex-a15

Clang doesn't support -mtune=cortex-a15 and newer ones will error out if this
is assigned.

Change-Id: Idf3b8850314717f99d0cdda65490f5af5c336fc8

Conflicts:
	Android.mk