Compile with newer openal-soft

src/eventthread.cpp

@@ -30,7 +30,6 @@
 #include <SDL_rect.h>
 
 #include <al.h>
-#include <alc.h>
 #include <alext.h>
 
 #include "sharedstate.h"

src/eventthread.h

@@ -36,8 +36,9 @@
 
 #include <stdint.h>
 
+#include <alc.h>
+
 struct RGSSThreadData;
-typedef struct ALCdevice_struct ALCdevice;
 struct SDL_Window;
 union SDL_Event;