Because... The "clean" target in zView's Makefile is incomplete.
    It doesn't remove pdf/*.o.
    As a result, pdf/pdflib.o is distributed in the source archive by
    error !
    Then this file is not rebuilt when you type make.
    Finally, I'm right: you are mixing new object files with old ones :P
True true, once again, Vincent! Many thanks for this observation, I 
totally missed it. I was able to compile zView against newest 
libraries (freetype, fixed windom/ldg) with very little changes. It's 
very MP unfriendly (VA protocol I guess + 2-3 other places where it 
crashes) but except this it works really nice. I was able to open 
PDFs, huge JPGs, ... what a cool software!