Added missing ldap_pvt_thread_mutex_trylock function.

libraries/libldap_r/thr_posix.c

@@ -195,6 +195,12 @@ ldap_pvt_thread_mutex_lock( ldap_pvt_thread_mutex_t *mutex )
 	return pthread_mutex_lock( mutex );
 }
 
+int 
+ldap_pvt_thread_mutex_trylock( ldap_pvt_thread_mutex_t *mutex )
+{
+	return pthread_mutex_trylock( mutex );
+}
+
 int 
 ldap_pvt_thread_mutex_unlock( ldap_pvt_thread_mutex_t *mutex )
 {