[Hexagon] Adding asr/lsr/asl reg/imm, asl with saturation, asr with rounding.  Doubleword abs/neg/not.  Interleave and deinterleave instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224365 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Adding bit count and twiddling instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224367 91177308-0d34-0410-b5e6-96231b3b80d8