Fix memory leak when creating SkBitmapProcShader

A SkShader is ref counted, but the first but unref() was
never called for the local reference in
PlatformGraphicsContextSkia::drawBitmapPattern().

Change-Id: Ia1936d62f052f9440ef0316cc642b0aebd79cfe1
libangle: build with -fno-strict-aliasing

Change-Id: Ic2e3f54799c07868ca44b2b0e900660cc4982970
Signed-off-by: Evan McClain <aeroevan@gmail.com>