Revert r200095 and r200152. It turns out when compiling with -arch armv7 -mcpu=cortex-m3, the triple would still set iOS as the OS so the hack is still needed. rdar://15984891

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200937 91177308-0d34-0410-b5e6-96231b3b80d8