* config/i386/mmx.md (mmxdoublemode): New mode attribute.
	(mmx_uavg<mode>3): Macroize expaner from mmx_uavgv8qi3 and
	mmx_uavgv4hi3 using MMXMODE12 mode iterator.
	(uavg<mode>3_ceil): New expander.
	* config/i386/sse.md (uavg<mode>3_ceil): Use ssedoublemode
	mode iterator when creating CONST1_RTX.
	(<sse2_avx2>_uavg<mode>3<mask_name>): Ditto.
	(*<sse2_avx2>_uavg<mode>3<mask_name>): Use ssedoublemode
	mode iterator for const1_operand predicate.

From-SVN: r274572