This patch adds instruction scheduling support for the Power8 processor. 
Bootstrap/regression test with no new failures. Ok for trunk?


2013-06-07  Michael Meissner  <meissner@linux.vnet.ibm.com>
         Pat Haugen <pthaugen@us.ibm.com>
         Peter Bergner <bergner@vnet.ibm.com>

     * 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.