[AArch64] Adding a TargetParser for AArch64

There's already a ARMTargetParser,now adding a similar one for aarch64.
so we can use it to do ARCH/CPU/FPU parsing in clang and llvm, instead of
string comparison.

Patch by Jojo Ma.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270687 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed