semunlink.c: Add missing _Objects_Allocator_unlock()

updates 2319.

Signed-off-by: Daniel Krueger <daniel.krueger@systec-electronic.com>

cpukit/posix/src/semunlink.c

@@ -46,6 +46,7 @@ int sem_unlink(
   status = _POSIX_Semaphore_Name_to_id( name, &the_semaphore_id, &name_len );
   if ( status != 0 ) {
     _Thread_Enable_dispatch();
+    _Objects_Allocator_unlock();
     rtems_set_errno_and_return_minus_one( status );
   }