Privileged ports to access the arbiter

[Joan Lledó]

Hi,

fortunately, after pulling last changes and updating hurd-libs0.3 I 
solved my problems with the arbiter being killed. Now I got my user 
clients getting the maps correctly, and wanted to go further and 
implement memory object proxy nesting and pci-arbiter nesting.

I found a problem there:

https://gitlab.freedesktop.org/xorg/lib/libpciaccess/-/blob/master/src/hurd_pci.c#L526

I can't run my nested arbiter as a non-privileged user b/c this line 
prevents me to connect to the main arbiter by lack of permissions. Why 
are why asking for privileges here? do we really need it?