Remove unneeded "using namespace"

The need for these must have got lost somewhere in the type cleanup.

unix/x0vncserver/XDesktop.cxx

 #include <x0vncserver/Geometry.h>
 #include <x0vncserver/XPixelBuffer.h>
 
-using namespace std;
 using namespace rfb;
 
 extern const unsigned short code_map_qnum_to_xorgevdev[];

vncviewer/CConn.cxx

 #include "win32.h"
 #endif
 
-using namespace rdr;
 using namespace rfb;
-using namespace std;
 
 static rfb::LogWriter vlog("CConn");
 

vncviewer/OptionsDialog.cxx

 #include <FL/Fl_Choice.H>
 
 using namespace std;
-using namespace rdr;
 using namespace rfb;
 
 std::map<OptionsCallback*, void*> OptionsDialog::callbacks;

vncviewer/Viewport.cxx

 
 
 using namespace rfb;
-using namespace rdr;
 
 static rfb::LogWriter vlog("Viewport");
 

vncviewer/vncviewer.cxx

 
 using namespace network;
 using namespace rfb;
-using namespace std;
 
 char vncServerName[VNCSERVERNAMELEN] = { '\0' };