[9.18] Merge branch 'feature/main/zt-rwlock.h' into 'main'
Include isc_rwlocktype_t type definition in zt.h
See merge request !7376 (merged)
(cherry picked from commit d7bcdf8b)
395d6fca Include isc_rwlocktype_t type definition in zt.h
Backport of MR !7376 (merged)