Optimize df_worklist_dataflow

[Jan Hubicka]

> > 	* 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.
> 
> Ping...

Ping^2 :)

Honza
> 
> Honza