kcc: fix sort for py3

py2:

    list.sort(cmp=None, key=None, reverse=False)
    sorted(iterable[, cmp[, key[, reverse]]])

py3:

    list.sort(key=None, reverse=False)
    sorted(iterable, *, key=None, reverse=False)

The `cmp` arg was removed in py3, make use of `key` arg to work around.

Signed-off-by: Joe Guo <joeg@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

python/samba/kcc/kcc_utils.py

@@ -1581,7 +1581,9 @@ class Site(object):
         # Which is a fancy way of saying "sort all the nTDSDSA objects
         # in the site by guid in ascending order".   Place sorted list
         # in D_sort[]
-        D_sort = sorted(self.rw_dsa_table.values(), cmp=sort_dsa_by_guid)
+        D_sort = sorted(
+            self.rw_dsa_table.values(),
+            key=lambda dsa: ndr_pack(dsa.dsa_guid))
 
         # double word number of 100 nanosecond intervals since 1600s
 
@@ -2221,11 +2223,6 @@ def get_dsa_config_rep(dsa):
                    dsa.dsa_dnstr)
 
 
-def sort_dsa_by_guid(dsa1, dsa2):
-    "use ndr_pack for GUID comparison, as appears correct in some places"""
-    return cmp(ndr_pack(dsa1.dsa_guid), ndr_pack(dsa2.dsa_guid))
-
-
 def new_connection_schedule():
     """Create a default schedule for an NTDSConnection or Sitelink. This
     is packed differently from the repltimes schedule used elsewhere