make MovieTexture_FFMpeg::RegisterProtocols available

stepmania/src/arch/MovieTexture/MovieTexture_FFMpeg.cpp

@@ -560,7 +560,7 @@ static avcodec::URLProtocol RageProtocol =
 	NULL
 };
 
-static void RegisterProtocols()
+void MovieTexture_FFMpeg::RegisterProtocols()
 {
 	static bool Done = false;
 	if( Done )

stepmania/src/arch/MovieTexture/MovieTexture_FFMpeg.h

@@ -35,6 +35,8 @@ public:
 	void SetLooping(bool looping=true) { m_bLoop = looping; }
 	unsigned GetTexHandle() const { return m_uTexHandle; }
 
+	static void RegisterProtocols();
+
 private:
 	FFMpeg_Helper *decoder;