remove llvm.part.set.* and llvm.part.select.*. They have never been

remove llvm.part.set.* and llvm.part.select.*.  They have never been
implemented in codegen, have no frontend to generate them, and are
better implemented with pattern matching (like the ppc backend does
to generate rlwimi/rlwinm etc).

PR4543

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75430 91177308-0d34-0410-b5e6-96231b3b80d8