Add scheduler classes for integer/float horizontal operations

[RKSimon]

Bugzilla Link	32801
Resolution	FIXED
Resolved on	Jun 08, 2017 10:26
Version	trunk
OS	Windows NT
Blocks	#31672 #27233
CC	@rotateright

Extended Description

The integer/float horizontal operations (PHADD, PHSUBD, HADDPS etc.) often have very different latency/throughput characteristics to basic 'in-element' arithmetic instructions.

They need separating from the existing classes and grouped into their own integer/float classes to allow better scheduling (Bug #​32325) and MC optimization (Bug #​26859).

[RKSimon]

rL304986