[X86][SSE] Missing SSE/AVX1 memory folding integer instructions

Added most of the missing integer vector folding patterns for SSE (to SSE42) and AVX1.

The most useful of these are probably the i32/i64 extraction, i8/i16/i32/i64 insertions, zero/sign extension, unsigned saturation subtractions, i64 subtractions and the variable mask blends (pblendvb) - others include CLMUL, SSE42 string comparisons and bit tests.

Differential Revision: http://reviews.llvm.org/D7094

llvm-svn: 226745