Implement coalesce list with hash table instead of linked list.

Implement coalesce list with hash table instead of linked list.

	* tree-ssa-live.c (create_coalesce_list): Create a hash table.
	(COALESCE_HASH_FN): New.  Define hash function.
	(partition_pair_map_hash): New.  Hash value for a partition pair.
	(partition_pair_map_eq): New.  Equality for hash pairs.
	(create_coalesce_list): Create hash table.
	(delete_coalesce_list): Free hash table.
	(find_partition_pair): Find/create pairs in hash table.
	(compare_pairs):  Sort pairs in ascending order now.
	(num_coalesce_pairs): New.  Number of pairs in hash table.
	(struct partition_pair_iterator): Iterator struct for pair table.
	(first_partition_pair): Iterator function for first pair.
	(end_partition_pair_p): Iterator function for end of iteration.
	(next_partition_pair): Iterator function for next pair.
	(FOR_EACH_PARTITION_PAIR): Macro for iterating over pairs.
	(sort_coalesce_list): Sort pairs from hash table into an array.
	(pop_best_coalesce): Take pairs from the array.
	(dump_coalesce_list): Update to use hash table or sorted array.
	* tree-ssa-live.h (struct partition_pair_d): Remove next field.
	(struct coalesce_list_d): Add hash table related fields.

From-SVN: r119378