SDL_dynapi_procs.h: adjust SDL_CreateThread for os/2

src/dynapi/SDL_dynapi_procs.h

@@ -50,6 +50,8 @@ SDL_DYNAPI_PROC(int,SDL_snprintf,(SDL_OUT_Z_CAP(b) char *a, size_t b, SDL_PRINTF
 
 #if defined(__WIN32__) && !defined(HAVE_LIBC)
 SDL_DYNAPI_PROC(SDL_Thread*,SDL_CreateThread,(SDL_ThreadFunction a, const char *b, void *c, pfnSDL_CurrentBeginThread d, pfnSDL_CurrentEndThread e),(a,b,c,d,e),return)
+#elif defined(__OS2__)
+SDL_DYNAPI_PROC(SDL_Thread*,SDL_CreateThread,(SDL_ThreadFunction a, const char *b, void *c, pfnSDL_CurrentBeginThread d, pfnSDL_CurrentEndThread e),(a,b,c,d,e),return)
 #else
 SDL_DYNAPI_PROC(SDL_Thread*,SDL_CreateThread,(SDL_ThreadFunction a, const char *b, void *c),(a,b,c),return)
 #endif