df-problems.c (df_simulate_initialize_forwards): Set, don't clear, bits for...

df-problems.c (df_simulate_initialize_forwards): Set, don't clear, bits for artificial defs at the top of the block.

	* df-problems.c (df_simulate_initialize_forwards): Set, don't clear,
	bits for artificial defs at the top of the block.
	* fwprop.c (single_def_use_enter_block): Don't call it.

From-SVN: r158750