Support 64-bit vectorization for single-precision floating rounding operation.

Here's list the patch supported.
rint/nearbyint/ceil/floor/trunc/lrint/lceil/lfloor/round/lround.

gcc/ChangeLog:

	PR target/106910
	* config/i386/mmx.md (nearbyintv2sf2): New expander.
	(rintv2sf2): Ditto.
	(ceilv2sf2): Ditto.
	(lceilv2sfv2si2): Ditto.
	(floorv2sf2): Ditto.
	(lfloorv2sfv2si2): Ditto.
	(btruncv2sf2): Ditto.
	(lrintv2sfv2si2): Ditto.
	(roundv2sf2): Ditto.
	(lroundv2sfv2si2): Ditto.
	(*mmx_roundv2sf2): New define_insn.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr106910-1.c: New test.