Add isc_mutex_destroy() and isc_rwlock_destroy() calls missing from the commits that introduced the relevant isc_mutex_init() and isc_rwlock_init() calls:
None of these omissions affect any hot paths, so they are not expected to cause operational issues; correctness is the only concern here.
All of these were found using the technique implemented in !5631 (closed).
Also add a couple of missing
isc_refcount_destroy() calls found while looking at the surrounding
Blocks !5631 (closed)