* df-problems.c (df_rd_confluence_n, df_lr_confluence_n, df_live_confluence_n,
	df_byte_lr_confluence_n, df_md_confluence_n): Return true if something changed.
	* df.h (df_confluence_function_n): Return bool.
	* df-core.c (df_worklist_propagate_forward, df_worklist_propagate_backward):
	track changes and ages.
	(df_worklist_dataflow_doublequeue): Use bitmap iterator for main walk;
	track ages.
	* dse.c (dse_confluence_n): Return always true.

From-SVN: r161197