Fix enclosure status

Enclosure wasn't checking if file existed on disk.  Hence, if the
enclosure was reporting a file size of 0 (which matches the non-existent
file size, then it would set the status incorrectly to Enclosure::Downloaded.

src/enclosure.cpp

@@ -38,12 +38,14 @@ Enclosure::Enclosure(Entry *entry)
     m_playposition_dbsave = m_playposition;
 
     QFile file(path());
+    if (file.exists()) {
         if(file.size() == m_size) {
             m_status = Downloaded;
         } else {
-        if(file.exists()) {
             file.remove();
+            m_status = Downloadable;
         }
+    } else {
         m_status = Downloadable;
     }
 }