sse.md (*mov<mode>_internal): Merge with *mov<mode>_internal_rex64.
* config/i386/sse.md (*mov<mode>_internal): Merge with
*mov<mode>_internal_rex64. Use x64 and nox64 isa attributes.
Emit insn template depending on type attribute. Use
HAVE_AS_IX86_INTERUNIT_MOVQ to handle broken assemblers that require
movd instead of movq mnemonic for interunit moves. Rewrite mode
attribute calculation. Remove unit attribute calculation.
Set prefix attribute to maybe_vex for sselog1 and ssemov types.
Set prefix_data16 attribute for DImode ssemov types.
Use Ym instead of y for SSE-MMX conversion alternatives.
Reorder operand constraints.