Unlocks rec_mutex. If another thread is blocked in a
g_rec_mutex_lock() call for rec_mutex, it will become unblocked
and can lock rec_mutex itself.
Calling g_rec_mutex_unlock() on a recursive mutex that is not
locked by the current thread leads to undefined behaviour.
Since 2.32
Unlocks rec_mutex. If another thread is blocked in a g_rec_mutex_lock() call for rec_mutex, it will become unblocked and can lock rec_mutex itself. Calling g_rec_mutex_unlock() on a recursive mutex that is not locked by the current thread leads to undefined behaviour. Since 2.32