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/app/button-application.c

@@ -30,6 +30,9 @@ int key_to_button(int keyboard_key)
     int new_btn = BUTTON_NONE;
     switch (keyboard_key)
     {
+#if (CONFIG_PLATFORM & PLATFORM_MAEMO4)
+        case SDLK_ESCAPE:
+#endif
         case SDLK_KP7:
             new_btn = BUTTON_TOPLEFT;
             break;
@@ -37,6 +40,9 @@ int key_to_button(int keyboard_key)
         case SDLK_UP:
             new_btn = BUTTON_TOPMIDDLE;
             break;
+#if (CONFIG_PLATFORM & PLATFORM_MAEMO4)
+        case SDLK_F7:
+#endif
         case SDLK_KP9:
             new_btn = BUTTON_TOPRIGHT;
             break;
@@ -44,6 +50,10 @@ int key_to_button(int keyboard_key)
         case SDLK_LEFT:
             new_btn = BUTTON_MIDLEFT;
             break;
+#if (CONFIG_PLATFORM & PLATFORM_MAEMO)
+        case SDLK_RETURN:
+        case SDLK_KP_ENTER:
+#endif
         case SDLK_KP5:
             new_btn = BUTTON_CENTER;
             break;
@@ -51,6 +61,9 @@ int key_to_button(int keyboard_key)
         case SDLK_RIGHT:
             new_btn = BUTTON_MIDRIGHT;
             break;
+#if (CONFIG_PLATFORM & PLATFORM_MAEMO4)
+        case SDLK_F6:
+#endif
         case SDLK_KP1:
             new_btn = BUTTON_BOTTOMLEFT;
             break;
@@ -58,6 +71,9 @@ int key_to_button(int keyboard_key)
         case SDLK_DOWN:
             new_btn = BUTTON_BOTTOMMIDDLE;
             break;
+#if (CONFIG_PLATFORM & PLATFORM_MAEMO4)
+        case SDLK_F8:
+#endif
         case SDLK_KP3:
             new_btn = BUTTON_BOTTOMRIGHT;
             break;