skia/bench: Use -fno-strict-aliasing

Use -fno-strict-aliasing for the benchmark so we don't have to use
it globally

Change-Id: Ibe5b80587818058cbb4290fe694c0b5d4cdc75a0
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>