s4:provision_basedn_modify - fix the "auditPolicy" attribute

I had to think about how to encode the string 0x0001 (taken from Windows Server).
The problem is due to the "0" byte at the beginning of it. BASE64 encoding
seems a good method to do it.

source4/setup/provision_basedn_modify.ldif

@@ -4,8 +4,9 @@
 dn: ${DOMAINDN}
 changetype: modify
 -
+# This should be 0x0001, but the 0 byte is not allowed - therefore encoded
 replace: auditingPolicy
-auditingPolicy: 

+auditingPolicy:: AAE=
 -
 replace: creationTime
 creationTime: ${CREATTIME}