df.c (df_ref_create, [...]): Kill BB argument.

	* df.c (df_ref_create, df_ref_record_1, df_ref_record): Kill BB argument.
	* df.h (struct ref): Kill B.
	(DF_REF_BB, DF_REF_BBNO): Use BLOCK_FOR_INSN.

	* basic-block.h (PROP_EQUAL_NOTES): New flag.
	* flow.c (propagate_one_insn): Use it.
	(mark_used_regs): Handle NIL.

From-SVN: r49220