configure problem due to libpng dependency on zlib

[Andrew Marlow <apm35 student open ac uk>]

Hi,

I just tried to build dia 0.9.1 on Solaris 8 and found that
configure fails because libpng refers to zlib routines but
test programs that link with libpng do not also link
with zlib. This manifests as can't find a definition
of neither finite nor isinf (sic). The definitions
are there, it's the link that's failed.

Can some knowledgeable person please investigate?

Regards,

Andrew Marlow
----
There is an emerald here the size of a plover's egg!