initialized state of capability objects should be locked

[Neal H. Walfield]

When a capability object is returned to the user (via
hurd_cap_class_alloc), it is locked.  hurd_cap_class_alloc does the
lock manually.  When a capability is released, _hurd_cap_obj_dealloc
is called.  _hurd_cap_obj_dealloc takes a locked capability and
returns it to the slab after unlocking it.  We should change the
initialization state so that _hurd_cap_obj_constructor enters locked
objects into the slab thereby eliding this extra lock/unlock sequence.

Marcus, shall I commit a patch which does this?

Thanks,
Neal