Unified logic for computing target ABI in backend and front end by moving this common code to Support/TargetParser.

Modeled Triple::GNU after front end code (aapcs abi) and  updated tests that expect apcs abi.

Based heavily on a patch by Ana Pazos!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306768 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed