Port to Android API 36

* java/AndroidManifest.xml.in: Update targetSdkVersion to 36.

* java/INSTALL: Document revised compilation dependencies.

* java/org/gnu/emacs/EmacsActivity.java (interceptBackGesture):
New function.
(onCreate): Invoke the same to register back gesture callbacks
on Android 16 or better.

* java/org/gnu/emacs/EmacsWindow.java (onBackInvoked): New
function.

* src/keyboard.c (lispy_function_keys): Amend with new symbols
introduced in Android API 36.

java/org/gnu/emacs/EmacsWindow.java

@@ -58,6 +58,7 @@ import android.util.SparseArray;
 import android.util.Log;
 
 import android.os.Build;
+import android.os.SystemClock;
 
 /* This defines a window, which is a handle.  Windows represent a
    rectangular subset of the screen with their own contents.
@@ -890,6 +891,20 @@ public final class EmacsWindow extends EmacsHandleObject
     EmacsNative.sendWindowAction (this.handle, 0);
   }
 
+  /* Dispatch a back gesture invocation as a KeyPress event.  Lamentably
+     the platform does not appear to support reporting keyboard
+     modifiers with these events.  */
+
+  public void
+  onBackInvoked ()
+  {
+    long time = SystemClock.uptimeMillis ();
+    EmacsNative.sendKeyPress (this.handle, time, 0,
+			      KeyEvent.KEYCODE_BACK, 0);
+    EmacsNative.sendKeyRelease (this.handle, time, 0,
+				KeyEvent.KEYCODE_BACK, 0);
+  }
+
 
 
   /* Mouse and touch event handling.