Improve criteria for restoring fullscreen state on Android

* java/Makefile.in ($(CLASS_FILES) &): Touch all class files,
even those javac chose not to rebuild.

* java/org/gnu/emacs/EmacsActivity.java (onWindowFocusChanged):
Restore fullscreen state here.
(onResume): And not here.

java/org/gnu/emacs/EmacsActivity.java

@@ -241,6 +241,15 @@ public class EmacsActivity extends Activity
       {
 	focusedActivities.add (this);
 	lastFocusedActivity = this;
+
+	/* Update the window insets as the focus change may have
+	   changed the window insets as well, and the system does not
+	   automatically restore visibility flags.  */
+
+	if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN
+	    && Build.VERSION.SDK_INT < Build.VERSION_CODES.R
+	    && isFullscreen)
+	  syncFullscreenWith (window);
       }
     else
       focusedActivities.remove (this);
@@ -264,9 +273,6 @@ public class EmacsActivity extends Activity
   {
     isPaused = false;
 
-    /* Update the window insets.  */
-    syncFullscreenWith (window);
-
     EmacsWindowAttachmentManager.MANAGER.noticeDeiconified (this);
     super.onResume ();
   }