combine patterns for add-add fusion

combine patterns for add-add fusion

This patch adds a function to genfusion.pl to add a couple
more patterns so combine can do fusion of pairs of add and
vaddudm instructions.

gcc/ChangeLog:

	* config/rs6000/genfusion.pl (gen_addadd): New function.
	* config/rs6000/fusion.md: Regenerate file.
	* config/rs6000/rs6000-cpus.def: Add
	OPTION_MASK_P10_FUSION_2ADD to masks.
	* config/rs6000/rs6000.c (rs6000_option_override_internal):
	Handle default value of OPTION_MASK_P10_FUSION_2ADD.
	* config/rs6000/rs6000.opt: Add -mpower10-fusion-2add.

gcc/testsuite/ChangeLog:

	* gcc.target/powerpc/fusion-p10-addadd.c: New file.