Improve debug output of loop data prefetching.

Improve debug output of loop data prefetching.

	* tree-ssa-loop-prefetch.c (struct mem_ref_group, struct mem_ref):
	New "uid" fields to hold pretty-print IDs of group and ref.
	Memory references are now identified as <group_id>:<ref_id>
	instead of using [random] addresses.
	(dump_mem_details): Simplify, no functional change.
	(dump_mem_ref): Simplify and make output more concise.
	Replace couple of fprintf's throughout code with calls to dump_mem_ref.
	(find_or_create_group): Initialize group uid.
	(record_ref): Initialize ref uid.  Improve debug output.
	(prune_group_by_reuse, should_issue_prefetch_p,)
	(should_issue_prefetch_p, schedule_prefetches, issue_prefetch_ref,)
	(mark_nontemporal_store, determine_loop_nest_reuse):
	Improve debug output.

Change-Id: Ia594d5854de96183f3c5a669c161e5a9a73a29d7

From-SVN: r248925