quartz: Avoid reading past the end of a buffer (Valgrind).

dlls/quartz/filtermapper.c

@@ -425,7 +425,7 @@ static int add_data(struct Vector *v, const void *pData, int size)
 static int find_data(const struct Vector *v, const void *pData, int size)
 {
     int index;
-    for (index = 0; index < v->current; index++)
+    for (index = 0; index + size <= v->current; index++)
         if (!memcmp(v->pData + index, pData, size))
             return index;
     /* not found */