[ARM64/AArch64] Hook up CRC32 subtarget feature to the driver

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@207841 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM64/AArch64] Define the correct value for __ARM_NEON_FP

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@207842 91177308-0d34-0410-b5e6-96231b3b80d8
Add support for -march=bdver4.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@207848 91177308-0d34-0410-b5e6-96231b3b80d8