gEDA-dev: [pcb] patch: export some compile-time options (for external HIDs)

[Igor2]

Hi,

I've changed my mind, I will rather use GPMI's search paths and don't try
to put these files in PCB's dirs. Still I will need the execprefix and
host to see where to put the (symlink?) of the external hid .so which then
will pass control to GPMI.

Igor2