minidom: enable support for writing rxml self-closing elements

minidom/src/element.rs

@@ -357,6 +357,7 @@ impl Element {
             encoder.encode(writer::Item::Attribute(None, name, value), buf)?;
         }
 
+        if ! self.children.is_empty() {
             encoder.encode(writer::Item::ElementHeadEnd, buf)?;
 
             for child in &self.children {
@@ -370,6 +371,7 @@ impl Element {
                         el.write_to_inner(encoder, buf)?,
                 }
             }
+        }
 
         encoder.encode(writer::Item::ElementFoot, buf)?;