/*
* Update an LWP's cached credentials to mirror the process' master copy.
*
* This happens early in the syscall path, on user trap, and on LWP
* creation. A long-running LWP can also voluntarily choose to update
* its credentials by calling this routine. This may be called from
* LWP_CACHE_CREDS(), which checks l->l_cred != p->p_cred beforehand.
*/