ARM: move feature for Thumb2 pkhbt/pkhtb onto architectures.

There's not much functional change, but it really is an architectural feature
(on v6T2, v7A, v7R and v7EM) rather than something each CPU implements
individually.

The main functional change is the default behaviour you get when specifying
only "-triple".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276013 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed