libcore/luni: Use -fno-strict-aliasing for now

This will be reverted once we have a proper fix.

Change-Id: Iab4663a5f96ff9770371f54697aa872260037ac1
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
libcore: Better Enum fix for JDK 7

 * Jerome Pilliet suggests using a cast in the compareTo method instead of
   changing the field visibility. This is a much better fix.

Change-Id: I334105e0922225512a4d0a2d4b6c9c6ec71b9c51