re PR rtl-optimization/8705 ([HP-PA] ICE in emit_move_insn_1, at expr.c:3101)

	PR opt/8705
	* gcse.c (try_replace_reg): On a successful substitution of a constant
	into a single set, try to simplify the source of the set.
	* loop.c (scan_loop): Don't try to optimize a MODE_CC set with a
	constant source.

From-SVN: r66060