ARM: embedded v7 'darwin' doesn't get min-version defines.

Make sure armv7 doesn't get the iOS deployment version definitions when
it's being used for non-iOS.

rdar://15497681

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@195149 91177308-0d34-0410-b5e6-96231b3b80d8