Update Android port

* doc/emacs/android.texi (Android Startup): Document `content'
special directory.
* java/debug.sh (is_root): Improve /bin/tee detection.
* java/org/gnu/emacs/EmacsNative.java (EmacsNative): New
function `dup'.
* java/org/gnu/emacs/EmacsOpenActivity.java (EmacsOpenActivity)
(checkReadableOrCopy, onCreate): Create content directory names
when the file is not readable.
* java/org/gnu/emacs/EmacsService.java (EmacsService)
(openContentUri, checkContentUri): New functions.
* src/android.c (struct android_emacs_service): New methods.
(android_content_name_p, android_get_content_name)
(android_check_content_access): New function.
(android_fstatat, android_open): Implement opening content URIs.
(dup): Export to Java.
(android_init_emacs_service): Initialize new methods.
(android_faccessat): Implement content file names.

java/org/gnu/emacs/EmacsNative.java

@@ -31,6 +31,10 @@ public class EmacsNative
      initialization.  */
   private static final String[] libraryDeps;
 
+
+  /* Like `dup' in C.  */
+  public static native int dup (int fd);
+
   /* Obtain the fingerprint of this build of Emacs.  The fingerprint
      can be used to determine the dump file name.  */
   public static native String getFingerprint ();