power8.md: New.

power8.md: New.

	* config/rs6000/power8.md: New.
	* config/rs6000/rs6000-cpus.def (RS6000_CPU table): Adjust processor
	setting for power8 entry.
	* config/rs6000/t-rs6000 (MD_INCLUDES): Add power8.md.
	* config/rs6000/rs6000.c (is_microcoded_insn, is_cracked_insn): Adjust
	test for Power4/Power5 only.
	(insn_must_be_first_in_group, insn_must_be_last_in_group): Add Power8
	support.
	(force_new_group): Adjust comment.
	* config/rs6000/rs6000.md: Include power8.md.

Co-Authored-By: Pat Haugen <pthaugen@us.ibm.com>
Co-Authored-By: Peter Bergner <bergner@vnet.ibm.com>
From-SVN: r200423