This macro searches for an installed zlib library. If nothing
was specified when calling configure, it searches first in /usr/local
and then in /usr. If the --with-zlib=DIR is specified, it will try
to find it in DIR/include/zlib.h and DIR/lib/libz.a. If --without-zlib
is specified, the library is not searched at all.
If either the header file (zlib.h) or the library (libz) is not
found, the configuration exits on error, asking for a valid
zlib installation directory or --without-zlib.
The macro defines the symbol HAVE_LIBZ if the library is found. You should
use autoheader to include a definition for this symbol in a config.h
file. Sample usage in a C/C++ source is as follows:
#endif /* HAVE_LIBZ */