Remove unused includes

The struct control_event does not use mutexes, and net.h does not need
SDL_platform.h.

app/src/control_event.c

@@ -3,7 +3,6 @@
 #include <string.h>
 
 #include "buffer_util.h"
-#include "lock_util.h"
 #include "log.h"
 
 static void

app/src/control_event.h

@@ -3,7 +3,6 @@
 
 #include <stdbool.h>
 #include <stdint.h>
-#include <SDL2/SDL_mutex.h>
 
 #include "android/input.h"
 #include "android/keycodes.h"