Making camlibs and iolibs relocatable

I've recently added "binary wheels" to my Python interface to 
libgphoto2. These include pre-built copies of libgphoto2 v2.5.27 and are 
much quicker and easier for a user to install as they don't have to 
install libgphoto2 (development headers) and compile the interface files.

One problem I encountered was the hard coding of absolute paths into 
where libgphoto2 looks for its camlibs and iolibs. Luckily the CAMLIBS 
and IOLIBS environment variables solve that problem, but I'd rather they 
weren't labelled as for "broken/test installations".

-- 
Jim Easterbrook                 <http://www.jim-easterbrook.me.uk/>