- Change __builtin_ia32_palignr intrinsic type to match the pattern in clang.

- Add patterns to match the following MMX builtins:

   * __builtin_ia32_vec_init_v8qi
   * __builtin_ia32_vec_init_v4hi
   * __builtin_ia32_vec_init_v2si
   * __builtin_ia32_vec_ext_v2si

  These builtins do not correspond to a single MMX instruction. They will have
  to be lowered -- most likely in the back-end.

llvm-svn: 112881