Initial maemo platform support

Adds Nokia N900, N810 and N800 support.

Features:
- Introduce maemo specific platform defines
- Play audio in silent mode
- Stop playback on incoming calls
- Battery level readout
- Bluetooth headset support
- Save CPU by disabling screen updates if the display
  is off or the app doesn't have input focus
- N900: GStreamer audio backend

Kudos to kugel for the code review.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@29248 a1c6a512-1295-4272-9138-f99709370657

firmware/target/hosted/sdl/button-sdl.c

@@ -67,6 +67,8 @@ struct event_queue button_queue;
 
 static int btn = 0;    /* Hopefully keeps track of currently pressed keys... */
 
+int sdl_app_has_input_focus = 1;
+
 #ifdef HAS_BUTTON_HOLD
 bool hold_button_state = false;
 bool button_hold(void) {
@@ -209,11 +211,34 @@ static void mouse_event(SDL_MouseButtonEvent *event, bool button_up)
 
 static bool event_handler(SDL_Event *event)
 {
+    SDLKey ev_key;
+
     switch(event->type)
     {
+    case SDL_ACTIVEEVENT:
+        if (event->active.state & SDL_APPINPUTFOCUS)
+        {
+            if (event->active.gain == 1)
+                sdl_app_has_input_focus = 1;
+            else
+                sdl_app_has_input_focus = 0;
+        }
+        break;
     case SDL_KEYDOWN:
     case SDL_KEYUP:
-        button_event(event->key.keysym.sym, event->type == SDL_KEYDOWN);
+        ev_key = event->key.keysym.sym;
+#if (CONFIG_PLATFORM & PLATFORM_MAEMO5)
+        /* N900 with shared up/down cursor mapping. Seen on the German,
+           Finnish, Italian, French and Russian version. Probably more. */
+        if (event->key.keysym.mod & KMOD_MODE)
+        {
+            if (ev_key == SDLK_LEFT)
+                ev_key = SDLK_UP;
+            else if (ev_key == SDLK_RIGHT)
+                ev_key = SDLK_DOWN;
+        }
+#endif
+        button_event(ev_key, event->type == SDL_KEYDOWN);
         break;
 #ifdef HAVE_TOUCHSCREEN
     case SDL_MOUSEMOTION: