Fixed implicit declaration of SDL_Log() warning in joystick source for Android.

src/joystick/android/SDL_sysjoystick.c

@@ -35,6 +35,7 @@
 #include "SDL_hints.h"
 #include "SDL_assert.h"
 #include "SDL_timer.h"
+#include "SDL_log.h"
 #include "SDL_sysjoystick_c.h"
 #include "../SDL_joystick_c.h"
 #include "../../core/android/SDL_android.h"