New port: Anbernic RG Nano

A bit of context, this device is a clone of the FunKey-S with a different form factor, hardware is mostly identical, the relevant difference is it has audio out (via usb-c, adapter to 3.5mm is included), this is the reason why the FunKey-SDK is needed for bulding.

This port is based on the old SDL 1.2 code because the device doesn't have SDL2 support. Alongside what was supported in the SDL 1.2 builds this port supports battery level, charging status and backlight control.

Change-Id: I7fcb85be62748644b667c0efebabf59d6e9c5ade

apps/plugins/doom/i_video.c

@@ -633,6 +633,18 @@ void I_ShutdownGraphics(void)
 #define DOOMBUTTON_ESC     BUTTON_POWER
 #define DOOMBUTTON_MAP     BUTTON_PREV
 
+#elif CONFIG_KEYPAD == RG_NANO_PAD
+#define DOOMBUTTON_UP      BUTTON_UP
+#define DOOMBUTTON_DOWN    BUTTON_DOWN
+#define DOOMBUTTON_LEFT    BUTTON_LEFT
+#define DOOMBUTTON_RIGHT   BUTTON_RIGHT
+#define DOOMBUTTON_SHOOT   BUTTON_R
+#define DOOMBUTTON_OPEN    BUTTON_B
+#define DOOMBUTTON_ESC     BUTTON_START
+#define DOOMBUTTON_ENTER   BUTTON_A
+#define DOOMBUTTON_WEAPON  BUTTON_X
+#define DOOMBUTTON_MAP     BUTTON_Y
+
 #else
 #error Keymap not defined!
 #endif

apps/plugins/doom/rockdoom.c

@@ -202,7 +202,11 @@ const unsigned char versions_builtin[7][20] =
    "TNT"
 };
 
+#ifdef RG_NANO /* Path is a bit longer */
+const unsigned char wads_builtin[7][34] =
+#else
 const unsigned char wads_builtin[7][30] =
+#endif
 {
    GAMEBASE"doom1.wad",
    GAMEBASE"doom.wad",