Add $DISPLAY to kdesktop_lock_lockfile file name.

This resolves bug 2998.

Thanks to Russell Brown for analyzing the problem and propose a solution.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit d3834ad4f5)

kdesktop/lock/main.cc

@@ -325,7 +325,7 @@ int main( int argc, char **argv )
 #endif
         }
 
-        TDELockFile lock(locateLocal("tmp", "kdesktop_lock_lockfile"));
+        TDELockFile lock(locateLocal("tmp", TQString("kdesktop_lock_lockfile.%1").arg(getenv("DISPLAY"))));
         lock.setStaleTime(0);
         TDELockFile::LockResult lockRet = lock.lock();
         if (lockRet != TDELockFile::LockOK) {