msvcrt/tests: Fix the %n format test for Vista.

dlls/msvcrt/tests/printf.c

@@ -390,9 +390,18 @@ static void test_sprintf( void )
     format = "asdf%n";
     x = 0;
     r = sprintf(buffer, format, &x );
-    ok(x == 4, "should write to x: %d\n", x);
-    ok(!strcmp(buffer,"asdf"), "failed\n");
-    ok( r==4, "return count wrong: %d\n", r);
+    if (r == -1)
+    {
+        /* %n format is disabled by default on vista */
+        /* FIXME: should test with _set_printf_count_output */
+        ok(x == 0, "should not write to x: %d\n", x);
+    }
+    else
+    {
+        ok(x == 4, "should write to x: %d\n", x);
+        ok(!strcmp(buffer,"asdf"), "failed\n");
+        ok( r==4, "return count wrong: %d\n", r);
+    }
 
     format = "%-1d";
     r = sprintf(buffer, format,2);