Actually use the return value in initialize_with_format callback call.

src/cubeb_opensl.cpp

@@ -985,9 +985,7 @@ initialize_with_format(cubeb_stream * stm, cubeb_stream_params * params,
     format_sample_rate = &pcm_format.samplesPerSec;
   }
 
-  func(format, format_sample_rate, using_floats);
-
-  return CUBEB_OK;
+  return func(format, format_sample_rate, using_floats);
 }
 
 static int