mobile/undo: set undo stack as clean after save

If we're using the undo stack for determining the whether there are
unsaved changes, we have to mark the undo stack as clean after save.

This duplicates code from desktop. It is planned to unify this in
the near future.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

mobile-widgets/qmlmanager.cpp

@@ -1341,6 +1341,7 @@ void QMLManager::saveChangesLocal()
 			return;
 		}
 		mark_divelist_changed(false);
+		Command::setClean();
 	} else {
 		appendTextToLog("local save requested with no unsaved changes");
 	}