* tree-ssa-dce.c (DCE_TODOs): New.
	(propagate_necessity): Return if something changed.
	(eliminate_unnecessary_stmts): Likewise.
	(perform_tree_ssa_dce): Return TODO flags when needed.
	(pass_dce, pass_dce_loop, pass_cd_dce): Remove TODO flags.

From-SVN: r120797