fix open return check

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@13858 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

ffserver.c

@@ -392,13 +392,13 @@ static void start_children(FFStream *feed)
 
                 if (!ffserver_debug) {
                     i = open("/dev/null", O_RDWR);
-                    if (i)
+                    if (i != -1) {
                         dup2(i, 0);
                         dup2(i, 1);
                         dup2(i, 2);
-                    if (i)
                         close(i);
                     }
+                }
 
                 av_strlcpy(pathname, my_program_name, sizeof(pathname));