Hi Guix,

the attached patch applies after the one adding gEDA/gaf[1], which is
still awaiting review.

In packaging PCB I noticed that our Mesa package loads a few libraries
with dlopen() but does not use absolute paths to store items.  In the
case of PCB, dlopen("libudev.so.0") fails and causes "pcb" die on
startup with a segfault.  To prevent this until the Mesa package is
fixed I wrapped the executable.

~~ Ricardo

[1]: https://lists.gnu.org/archive/html/guix-devel/2015-03/msg00205.html