Updated the ARCH selector to match what Apple uses. Otherwise the Xcode UI gets
two entries because of the different patterns (Apple now defaults to also
including this). All this needs to match is x86_64, arm64, and maybe ppc64.

DELTA=1  (0 added, 0 deleted, 1 changed)

git-svn-id: http://google-toolbox-for-mac.googlecode.com/svn/trunk@634 7dc7ac4e-7543-0410-b95c-c1676fc8e2a3