Fix testsuite/gcc.dg/vect/vect-strided-a-u16-i4.c

[Jan Hubicka]

Hi,
this testcase has volatile variable read to prevent vectorization but then
it is shadowed by local var of the same name. Currently it prevents 
vectorization
but not reliably (i.e. we can manage to optimize the conditional away from loop
since it is invariant and that is what happens in my tree.)

        * gcc.dg/vect/vect-strided-a-u16-i4.c: Rename volatile variable to avoid
        shadowing.

Index: testsuite/gcc.dg/vect/vect-strided-a-u16-i4.c
===================================================================
--- testsuite/gcc.dg/vect/vect-strided-a-u16-i4.c       (revision 199343)
+++ testsuite/gcc.dg/vect/vect-strided-a-u16-i4.c       (working copy)
@@ -12,7 +12,7 @@ typedef struct {
    unsigned short d;
 } s;
 
-volatile int y = 0;
+volatile int yy = 0;
 
 __attribute__ ((noinline)) int
 main1 ()
@@ -29,7 +29,7 @@ main1 ()
       arr[i].b = i * 2;
       arr[i].c = 17;
       arr[i].d = i+34;
-      if (y) /* Avoid vectorization.  */
+      if (yy) /* Avoid vectorization.  */
         abort ();
     }