Remove some more causes of warnings.

audio_ao.c

@@ -41,9 +41,9 @@ static void help(void) {
 }
 
 static int init(int argc, char **argv) {
-  const char *str;
-  int value;
-  double dvalue;
+  // const char *str;
+  // int value;
+  // double dvalue;
   ao_initialize();
   int driver = ao_default_driver_id();
   ao_option *ao_opts = NULL;