pkg-config search path

[Havoc Pennington]

Hi,

I think the right solution is probably to add a config file similar to
ld.so.conf that lists pkg-config search dirs, and ship it by default
with X11R6 in there.

I've entertained the option of searching the system library path before;
some issues are:

 - I'm not sure how complicated it is to reconstruct this path
     using LD_LIBRARY_PATH, ld.so.conf, etc.
 - I'm not sure how much of LD_LIBRARY_PATH/ld.so.conf is 
     at all portable/standard and kind of suspect the answer 
     is "none of it"
 - Owen has raised the issue of arch-independent .pc files 
     in datadir

Havoc