Fixed possible SIGCHILD signal lost

When multiple(eg. 20) xrdp connections are disconnected at the same time(eg.  close all rdp client at the same time), zombie process may be spawned.

sesman/sig.c

@@ -122,12 +122,16 @@ sig_sesman_session_end(int sig)
         return;
     }
 
-    pid = g_waitchild();
-
-    if (pid > 0)
+    do
     {
-        session_kill(pid);
+        pid = g_waitchild();
+
+        if (pid > 0)
+        {
+            session_kill(pid);
+        }
     }
+    while (pid >= 0);
 }
 
 /******************************************************************************/

xrdp/xrdp.c

@@ -163,9 +163,7 @@ xrdp_shutdown(int sig)
 static void
 xrdp_child(int sig)
 {
-    int safety;
-
-    for (safety = 0; (g_waitchild() >= 0) && (safety <= 10); safety++)
+    while (g_waitchild() >= 0)
     {
     }
 }