Add emacsclient desktop file equivalent on Android

* doc/emacs/android.texi (Android File System):
* java/AndroidManifest.xml.in: Update with new activity.  Remove
Android 10 restrictions through a special flag.

* java/org/gnu/emacs/EmacsNative.java (getProcName): New
function.
* java/org/gnu/emacs/EmacsOpenActivity.java (EmacsOpenActivity):
New file.
* java/org/gnu/emacs/EmacsService.java (getLibraryDirection):
Remove unused annotation.
* lib-src/emacsclient.c (decode_options): Set alt_display on
Android.
* src/android.c (android_proc_name): New function.
(NATIVE_NAME): Export via JNI.

java/org/gnu/emacs/EmacsNative.java

@@ -153,6 +153,10 @@ public class EmacsNative
   public static native long sendExpose (short window, int x, int y,
 					int width, int height);
 
+  /* Return the file name associated with the specified file
+     descriptor, or NULL if there is none.  */
+  public static native byte[] getProcName (int fd);
+
   static
   {
     System.loadLibrary ("emacs");