prevent KDE/Qt from interfering with the session manager

I occassionally get lockups in IceProcessMessages() called from QtCore,
I'm actually not exactly sure why, as theoretically two connections
from one app shouldn't be a problem, but since LO does its own
session handling, there's no need to the KDE/Qt code to be involved,
so prevent it from connecting to the session manager altogether.

Change-Id: Iebe20d4cb5403e5fea8bd5d8c1f69b62d1c2907b

vcl/unx/kde4/KDEXLib.cxx

@@ -166,8 +166,23 @@ void KDEXLib::Init()
 
     KCmdLineArgs::init( m_nFakeCmdLineArgs, m_pAppCmdLineArgs, kAboutData );
 
+    // LO does its own session management, so prevent KDE/Qt from interfering
+    // (QApplication::disableSessionManagement(false) wouldn't quite do,
+    // since that still actually connects to the session manager, it just
+    // won't save the application data on session shutdown).
+    char* session_manager = NULL;
+    if( getenv( "SESSION_MANAGER" ) != NULL )
+    {
+        session_manager = strdup( getenv( "SESSION_MANAGER" ));
+        unsetenv( "SESSION_MANAGER" );
+    }
     m_pApplication = new VCLKDEApplication();
-    kapp->disableSessionManagement();
+    if( session_manager != NULL )
+    {
+        setenv( "SESSION_MANAGER", session_manager, 1 );
+        free( session_manager );
+    }
+
     KApplication::setQuitOnLastWindowClosed(false);
 
 #if KDE_HAVE_GLIB

vcl/unx/kde4/VCLKDEApplication.hxx

@@ -21,22 +21,14 @@
 
 #define Region QtXRegion
 
-#include <QSessionManager>
-
 #include <kapplication.h>
 
 #undef Region
 
-/* #i59042# override KApplications method for session management
- * since it will interfere badly with our own.
- */
 class VCLKDEApplication : public KApplication
 {
     public:
         VCLKDEApplication();
-
-        virtual void commitData(QSessionManager&) {};
-
         virtual bool x11EventFilter(XEvent* event);
 };