Best way to fix a preprocessor / linker mismatch in pkgsrc

[Emmanuel Kasper <emmanuel%libera.cc@localhost>]

 Hello
I submited a pr ( 
http://mail-index.netbsd.org/pkgsrc-bugs/2010/08/28/msg039357.html ), 
AFAIK on my system pkgsrc picked the OS headers for libiconv, and then 
tried to link with the pkgsrc library.
What is the best way to fix such a problem ? Should I instruct the 
Linker to use the system libiconv, or force the package to include the 
headers file from pkgsrc ?
Also more generally, is there a recommandation to use native libraries 
againts pkgsrc libraries when building packages, or is it something left 
for the user to choose  ?
Thank you
Emmanuel

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