[Hexagon] Adding accumulating add/sub, doubleword logic-not variants, doubleword bitfield extract, word parity, accumulating multiplies with saturation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225024 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "merge consecutive stores of extracted vector elements"

This reverts commit r224611. This change causes crashes
in X86 DAG->DAG Instruction Selection.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225031 91177308-0d34-0410-b5e6-96231b3b80d8