* lib/windows-mutex.h (glwthread_mutex_t): Add 'owner' field.
* lib/windows-mutex.c: Include <stdlib.h>.
(glwthread_mutex_lock): Set the 'owner' field after entering the
critical section.
(glwthread_mutex_trylock): Detect whether the lock was previously locked
by this thread. Set the 'owner' field after entering the critical
section.
(glwthread_mutex_unlock): Clear the 'owner' field before leaving the
critical section.
* lib/windows-timedmutex.h (glwthread_timedmutex_t): Add 'owner' field.
* lib/windows-timedmutex.c: (glwthread_timedmutex_lock): Set the 'owner'
field after entering the critical section.
(glwthread_timedmutex_trylock): Detect whether the lock was previously
locked by this thread. Set the 'owner' field after entering the critical
section.
(glwthread_timedmutex_unlock): Clear the 'owner' field before leaving
the critical section.