required autotools macro written and deployed in all apropriate Makefile.ams.
Use cases checked:
- linux, standard location of zlib, no ndb
- linux, standard locatoin of zlib, with ndb
- linux, non-standard location of zlib, no ndb
- hpux11, use of bundled zlib, no ndb 
The only non-checked case is non-standard location of zlib (or use of bundled
zlib) + ndb. I wasn't able to check it as ndb/ just won't compile on beasts 
like AIX52 or HPUX11, where such a check is possible. It didn't compile 
there before as these systems dont't have installed zlib, so nothing got broken ;)