AX_BOOST_BASE m4 macro and /usr/lib64 libraries

[Michal H. <ms...@gm...>]

Hi Thomas.
We (PDFedit project - http://sourceforge.net/projects/pdfedit) are using
your boost macros for correct boost libraries and headers detection
(namely AX_BOOST_BASE and AX_BOOST_IOSTREAMS).
Until now, everything was ok and we had no problem with almost all
distributions. However Altlinux 64b seems to handle libraries in
different way - they are stored under /usr/lib64 directory. 
Your (AX_BOOST_BASE) script relies on ac_boost_path and libraries are
hardcoded as $ac_boost_path/lib and there is no way to for something
else. 
I don't know, how to fix that because I am not familiar with different
deployments of boost in the systems, so I have created a workaround.
It is based on the new --with-boost-lib parameter which forces this
directory to be used for libraries. If you don't use it then all
detection is kept as in original implementation.

What do you think about this change?
Is there some other solution?

Feel free to use this patch for your purposes.

Best regards
-- 
Michal Hocko