bug#45202: pcscd service (pcsc-lite) doesn't handle run directory properly

[Raffael Stocker <r.stocker@mnet-mail.de>]

Hi,

I use the pcsc-lite package and noticed that the pcscd service is
sometimes not started by shepherd/herd.  If it is started, "herd start
pcscd" gives me the following error message (sorry for the german part):

> herd: Ausnahmefehler während der Ausführung von »start« mit dem Dienst »pcscd«:
> In procedure open-file: No such file or directory: "/var/run/pcscd/pcscd.pid"

The reason seems to be that pcsc-lite creates its pid file in
"/run/pcscd/", but herd expects it in "/var/run/pcscd/".  This leads to
the service not being started when the files in "/run/pcscd/" have not
been cleaned up (or so my interpretation).  In this case, I get the
error message:

> herd: Ausnahmefehler während der Ausführung von »start« mit dem Dienst »pcscd«:
> Throw to key `%exception' with args `("#<&invoke-error program:
> \"/gnu/store/r1yd6czv3r0is0a1gfsrix3gslkba80v-pcsc-lite-1.9.0/sbin/pcscd\"
> arguments: () exit-status: 1 term-signal: #f stop-signal: #f>")'. 

If I delete the "/run/pcscd" directory, the daemon will be started,
although with the first error message from above.

I have been using guix for only a week now and don't know how to edit
service definitions etc., but maybe someone more competent could have a
look at this.

Regards,
Raffael