Update Android port

* doc/emacs/android.texi (Android Windowing): Document how to
pass multimedia keys to the system.
* java/org/gnu/emacs/EmacsNative.java (EmacsNative): New
function.
* java/org/gnu/emacs/EmacsView.java (onKeyDown, onKeyMultiple)
(onKeyUp): Check that function.
* java/org/gnu/emacs/EmacsWindow.java (defineCursor): Handle
cases where cursor is NULL.
* src/android.c (NATIVE_NAME): New function.
* src/androidfns.c (syms_of_androidfns): New variable.
* src/keyboard.c (lispy_function_keys): Add volume keys.

java/org/gnu/emacs/EmacsNative.java

@@ -174,6 +174,10 @@ public final class EmacsNative
      main thread's looper to respond.  */
   public static native void endSynchronous ();
 
+  /* Return whether or not KEYCODE_VOLUME_DOWN, KEYCODE_VOLUME_UP and
+     KEYCODE_VOLUME_MUTE should be forwarded to Emacs.  */
+  public static native boolean shouldForwardMultimediaButtons ();
+
 
 
   /* Input connection functions.  These mostly correspond to their