Build the dummy joystick driver on Android

Fixes https://github.com/libsdl-org/SDL/issues/9978

Android.mk

@@ -40,6 +40,7 @@ LOCAL_SRC_FILES := \
 	$(wildcard $(LOCAL_PATH)/src/hidapi/*.c) \
 	$(wildcard $(LOCAL_PATH)/src/hidapi/android/*.cpp) \
 	$(wildcard $(LOCAL_PATH)/src/joystick/*.c) \
+	$(wildcard $(LOCAL_PATH)/src/joystick/dummy/*.c) \
 	$(wildcard $(LOCAL_PATH)/src/joystick/android/*.c) \
 	$(wildcard $(LOCAL_PATH)/src/joystick/hidapi/*.c) \
 	$(wildcard $(LOCAL_PATH)/src/joystick/virtual/*.c) \