Emit vmov.i64 to load 0.0 into FP reg when neon enabled.

Emit vmov.i64 to load 0.0 into FP reg when neon enabled.

	* config/arm/arm.md: (arch): Add neon.
	(arch_enabled): Return yes for arch neon when TARGET_NEON.
	* config/arm/vfp.md (movdf_vfp): Add w/G as alternative 3.  Add
	neon_move as type for alt 3.  Add arch attr enabling alt 3 for neon.
	Emit vmov.i64 for alt 3.  Renumber alternatives 3 to 8.  Adjust
	attributes for alt renumbering.  Mark alt 3 as non-predicable.
	(thumb2_movdf_vfp): Likewise.

From-SVN: r235998