re PR bootstrap/51796 (internal compiler error: in distribute_notes, at combine.c:13285 for libgomp/alloc.c on m68k-linux)

	PR bootstrap/51796
	* combine.c (distribute_notes): If i3 is a noreturn call,
	allow old_size to be equal to args_size and make sure the
	noreturn call gets REG_ARGS_SIZE note.
	* expr.c (fixup_args_size_notes): Put REG_ARGS_SIZE notes
	on noreturn calls even when the delta is 0.

	* gcc.dg/pr51796.c: New test.

From-SVN: r183111