re PR rtl-optimization/91136 (incorrect move of instruction to delay slot causes application crash in exception handling)

	PR rtl-optimization/91136
	* df-core.c (ACCESSING REFS): Fix typos in comment.
	* resource.c (mark_target_live_reg): Add artificial defs that occur at
	the beginning of the block to the initial set of live registers.

From-SVN: r273436