ia64.c (ia64_single_set): Return first set for prologue_allocate_stack and epilogue_deallocate_stack...

	* config/ia64/ia64.c (ia64_single_set): Return first set for
	prologue_allocate_stack and epilogue_deallocate_stack instructions.

	* gcc.c-torture/compile/20011219-1.c: New test.

From-SVN: r48187