porting problem: linuxish paths in configure

[Piero]

Hi,

I am trying to port an application to FreeBSD. This is a devel GTK2 
based version of polish/gnugadu instant messenger. This requires for 
its default gadu-gadu (Polish IM network) functionality libgadu 
library, that comes with the polish/ekg port.

The ekg port obeys FreeBSD hier, having all the files, libraries and 
headers installed in /usr/local prefix. The issue is that gnugadu2 
is trying to search for its headers in /usr/include instead of 
/usr/local/include. Making symlinks to /usr/local/include/libgadu* 
was the unique workaround I could find to make it configure and then 
build. And I know it is the Wrong Way.

I was grepping files in search of the wrong paths, but it didn't 
lead me too fur. I do not know where exactly I should look for the 
reasons of the problem and which file is to be patched. I am not a 
coder, but am willing to learn what is needed to solve it. 

Could you guys, being more experienced point me into the right 
direction where I could find solution. Here go configure files:
http://www.poprostu.pl/~smyru/gnome if more is needed here is a 
source: http://heanet.dl.sourceforge.net/sourceforge/ggadu/gg2-2.
0pre3.tar.gz

I would also be grateful for any advice about what I need to learn 
(autoconf, I guess) to be able solve such things on myself in the 
future. 

Thanks,
--
 Piero
 piero at poprostu.pl