Fix Coverity issues:
CID
1021635 (#1 of 2): Unchecked return value (CHECKED_RETURN)7.
check_return: Calling pthread_mutex_unlock without checking return value
(as is done elsewhere 29 out of 33 times).
CID
1021634 (#2 of 2): Unchecked return value (CHECKED_RETURN)12.
check_return: Calling pthread_mutex_unlock without checking return value
(as is done elsewhere 29 out of 33 times).
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>