s4:provision Fix provision on FreeBSD

We were missing the 'cn' attribute, which we then prepare a sorted
list based on.  On Linux, strcmp(NULL, NULL) does not segfault, where
it does on FreeBSD.

Reported by Timur I. Bakeyev <timur@com.bat.ru>

Andrew Bartlett

source4/scripting/python/samba/ms_schema.py

@@ -226,6 +226,7 @@ def __transform_entry(entry, objectClass):
     assert(cn)
     entry.insert(0, ["dn", "CN=%s,${SCHEMADN}" % cn])
     entry.insert(1, ["objectClass", ["top", objectClass]])
+    entry.insert(2, ["cn", cn])
     
     for l in entry:
         key = l[0].lower()