cfgrtl.c (purge_dead_edges): Set BB_DRITY flags if edge has been removed; fix return value.

	* cfgrtl.c (purge_dead_edges): Set BB_DRITY flags if edge has been
	removed; fix return value.
	* combine.c (combine_instructions): Dirtify blocks where we failed to
	update liveness; purge dead edges; use update_life_info_in_dirty_blocks.
	* toplev.c (rest_of_compilation): Do not purge_dead_edges after combine.

From-SVN: r50454