db_flatstore: update timestamp for kamailio specific rpc rotate

- do also in 'rotate' command, not only in 'k_rotate'
- from a patch by Abdelkader Allam

(cherry picked from commit b15aefa31e45f1ad6a45b64905f9fae24e0f790e)
(cherry picked from commit d75bc3b69151a9d0391309e6bb51784f3b6b9a83)
usrloc: avoid double locking when preloading attributes

- reported by Seudin Kasumovic, FS#378

(cherry picked from commit 888635bfa3719afeeea6f5f0d407aa862ceb34ac)
(cherry picked from commit 8df9d2336e7de2648288cf8ff6821e6820d88da9)