Fix tdesu process handling

tdesu/process.cpp

@@ -491,9 +491,14 @@ int PtyProcess::waitForChild()
     FD_ZERO(&fds);
 
     while (1) 
+    {
+        int ret = 0;
+
+        if (m_Fd != -1)
         {
             FD_SET(m_Fd, &fds);
-        int ret = select(m_Fd+1, &fds, 0L, 0L, 0L);
+            ret = select(m_Fd+1, &fds, 0L, 0L, 0L);
+        }
         if (ret == -1) 
         {
             if (errno != EINTR)