Cleaned the $path variable to fix mixed slashes

I needed to clean the $path contents since it will be used later when trying to remove it from the subfolder's full path. It is cleaned inside of JFolder::folders, but only in the scope of that function. It needs to be cleaned before it is used by JFolder::folder

libraries/joomla/form/fields/folderlist.php

@@ -198,6 +198,9 @@ protected function getOptions()
 			$options[] = JHtml::_('select.option', '', JText::alt('JOPTION_USE_DEFAULT', preg_replace('/[^a-zA-Z0-9_\-]/', '_', $this->fieldname)));
 		}
 
+		// Clean the $path contents
+		$path = JPath::clean($path);
+
 		// Get a list of folders in the search path with the given filter.
 		$folders = JFolder::folders($path, $this->filter, $this->recursive, true);