[X86] add an exedepfix entry for movq == movlps == movlpd

This is a 1-line patch (with a TODO for AVX because that will affect
even more regression tests) that lets us substitute the appropriate
64-bit store for the float/double/int domains.

It's not clear to me exactly what the difference is between the 0xD6 (MOVPQI2QImr) and 
0x7E (MOVSDto64mr) opcodes, but this is apparently the right choice.

Differential Revision: http://reviews.llvm.org/D8691

llvm-svn: 235014