Cleanup modref interfaces.

Cleanup modref interfaces.

	* ipa-fnsummary.c (refs_local_or_readonly_memory_p): New function.
	(points_to_local_or_readonly_memory_p): New function.
	* ipa-fnsummary.h (refs_local_or_readonly_memory_p): Declare.
	(points_to_local_or_readonly_memory_p): Declare.
	* ipa-modref.c (record_access_p): Use refs_local_or_readonly_memory_p.
	* ipa-pure-const.c (check_op): Likewise.

	* gcc.dg/tree-ssa/local-pure-const.c: Update template.