DHCP postLdapSave should lock the object modified

From the code: /* FIXME - We should lock the object and check if we don’t erase changes */

(from redmine: issue id 5340, created on 2017-01-24, closed on 2017-06-12)

• Relations:
  • copied_to #5346 (closed)
• Changesets:
  • Revision 1ed06643 by Côme Chilliet on 2017-06-08T12:53:15.000Z:

Fixes #5340 Locking the DHCP configuration when we modify it

• Custom Fields:
  • Support contract: None
  • Dolibarr project Name: PJ1610-0019