fix error when compiling without libswresample

panda/src/ffmpeg/ffmpegAudioCursor.cxx

@@ -52,9 +52,11 @@ FfmpegAudioCursor(FfmpegAudio *src) :
   _packet_data(0),
   _format_ctx(0),
   _audio_ctx(0),
+#ifdef HAVE_SWRESAMPLE
+  _resample_ctx(0),
+#endif
   _buffer(0),
-  _buffer_alloc(0),
-  _resample_ctx(0)
+  _buffer_alloc(0)
 {
   if (!_ffvfile.open_vfs(_filename)) {
     cleanup();