> definition of _fexist in section (__TEXT,__text)
> ld: multiple definitions of symbol _linput

?? maybe due to the merging of all symbols between 
httrack.o and the library.. 

What I can't understand is that httrack successfully 
compiled on 10 different platforms, including very exotic 
ones (s390, ia64, sun..), but there has been multiple 
problems with OSX since the begining :(

Can you try this:

rgrep RTLD_LAZY /usr/include/* /usr/local/include/* 
2>/dev/null

Can you also email me the complete log of the standard 
build (./configure && make) ?