gcc.dg/torture/pr113255.c: Fix ia32 test failure

Fix ia32 test failure:

FAIL: gcc.dg/torture/pr113255.c   -O1  (test for excess errors)
Excess errors:
cc1: error: '-mstringop-strategy=rep_8byte' not supported for 32-bit code

	PR rtl-optimization/113255
	* gcc.dg/torture/pr113255.c (dg-additional-options): Add only
	if not ia32.

gcc/testsuite/gcc.dg/torture/pr113255.c

 /* { dg-do run } */
-/* { dg-additional-options "-mtune=k8 -mstringop-strategy=rep_8byte" { target { x86_64-*-* i?86-*-* } } } */
+/* { dg-additional-options "-mtune=k8 -mstringop-strategy=rep_8byte" { target { { i?86-*-* x86_64-*-* } && { ! ia32 } } } } */
 
 struct S { unsigned a[10]; unsigned y; unsigned b[6]; } g[2];