ffserver: free nacl as needed

Should fix FFmpeg Coverity Scan issue #732268
Signed-off-by: Reynaldo H. Verdejo Pinochet <r.verdejo@sisa.samsung.com>

ffserver.c

@@ -1365,7 +1365,8 @@ static void parse_acl_row(FFStream *stream, FFStream* feed, IPAddressACL *ext_ac
                 naclp = &(*naclp)->next;
 
             *naclp = nacl;
-        }
+        } else
+            av_free(nacl);
     }
 }