[X86] Implement broadcastf32x2 and broadcasti32x2 intrinsics using...

[X86] Implement broadcastf32x2 and broadcasti32x2 intrinsics using __builtin_shufflevector instead builtins

This patch implements the broadcastf32x2/broadcasti32x2 intrinsics using __builtin_shufflevector.

Differential Revision: https://reviews.llvm.org/D37287

llvm-svn: 312135