Add /usr/lib/iptables as possible XTABLES_LIBDIR.

Author: ldx

iptc/xtables.py

@@ -683,7 +683,7 @@ class XTablesError(Exception):
 _xtables_libdir = os.getenv("XTABLES_LIBDIR")
 if _xtables_libdir is None:
     import os.path
-    for xtdir in ["/lib/xtables", "/usr/lib/xtables",
+    for xtdir in ["/lib/xtables", "/usr/lib/xtables", "/usr/lib/iptables",
                   "/usr/local/lib/xtables"]:
         if os.path.isdir(xtdir):
             _xtables_libdir = xtdir