llc: Add support for -mcpu=native.

When -mcpu=native is passed, autodetect the host CPU and pass that
as the CPU name to the TargetMachine factory method.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206095 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed