waver : fix data race with ggwave instance + v1.4.1

examples/ggwave-common-sdl2.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <string>
+#include <memory>
 
 class GGWave;
 
@@ -8,6 +9,7 @@ class GGWave;
 
 void GGWave_setDefaultCaptureDeviceName(std::string name);
 bool GGWave_init(const int playbackId, const int captureId, const int payloadLength = -1, const float sampleRateOffset = 0);
-GGWave *& GGWave_instance();
+std::shared_ptr<GGWave> GGWave_instance();
+void GGWave_reset(void * parameters);
 bool GGWave_mainLoop();
 bool GGWave_deinit();