[X86][XOP] Support for VPERMIL2PD/VPERMIL2PS 2-input shuffle instructions

This patch begins adding support for lowering to the XOP VPERMIL2PD/VPERMIL2PS shuffle instructions - adding the X86ISD::VPERMIL2 opcode and cleaning up the usage.

The internal llvm intrinsics were assuming the shuffle mask operand was the same type as the float/double input operands (I guess to simplify the intrinsic definitions in X86InstrXOP.td to a single value type). These needed changing to integer types (matching the clang builtin and the AMD intrinsics definitions), an auto upgrade path is added to convert old calls.

Mask decoding/target shuffle support will be added in future patches.

Differential Revision: http://reviews.llvm.org/D20049

llvm-svn: 271633