Fix build against old SDL2

Signed-off-by: falkTX <falktx@falktx.com>

distrho/src/jackbridge/SDL2Bridge.hpp

@@ -21,6 +21,14 @@
 
 #include <SDL.h>
 
+#ifndef SDL_HINT_AUDIO_DEVICE_APP_NAME
+# define SDL_HINT_AUDIO_DEVICE_APP_NAME "SDL_AUDIO_DEVICE_APP_NAME"
+#endif
+
+#ifndef SDL_HINT_AUDIO_DEVICE_STREAM_NAME
+# define SDL_HINT_AUDIO_DEVICE_STREAM_NAME "SDL_AUDIO_DEVICE_STREAM_NAME"
+#endif
+
 #if DISTRHO_PLUGIN_NUM_INPUTS+DISTRHO_PLUGIN_NUM_OUTPUTS == 0
 # error SDL without audio does not make sense
 #endif