rs6000: New iterator CCEITHER

rs6000: New iterator CCEITHER

This expands to both CC and CCUNS, it's useful for isel for example.

	* config/rs6000/rs6000.md (CCEITHER): New define_mode_iterator.
	(un): New define_mode_attr.
	(isel_signed_<mode>, isel_unsigned_<mode>): Delete, merge into ...
	(isel_<un>signed_<GPR:mode>): ... this.  New define_insn.
	(isel_reversed_signed_<mode>, isel_reversed_unsigned_<mode>): Delete,
	merge into ...
	(isel_reversed_<un>signed_<GPR:mode>): ... this.  New define_insn.

From-SVN: r272319