Set default CPU for Darwin targets with LTO. <rdar://problem/12457841>

This is a temporary hack until Bill's project to record command line options
in the LLVM IR is ready. Clang currently sets a default CPU but that isn't
recorded anywhere and it doesn't get used in the final LTO compilation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165809 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed