Use RemoteFile::isOpen() instead of Open() to check for success.

Calling Open() was unnecessarily creating extra socket connections to
the backend, and the original socket connections from calling Open()
in the constructor were leaking and accumulating in both the frontend
and backend (refs #11341).  Refs #11618

mythtv/libs/libmythtv/textsubtitleparser.cpp

@@ -147,7 +147,7 @@ bool TextSubtitleParser::LoadSubtitles(const QString &fileName,
 
     LOG(VB_VBI, LOG_INFO,
         QString("Preparing to load subtitle file (%1)").arg(fileName));
-    if (!rfile.Open())
+    if (!rfile.isOpen())
     {
         LOG(VB_VBI, LOG_INFO,
             QString("Failed to load subtitle file (%1)").arg(fileName));