> "ftp://ftp.gnuplot.info/pub/gnuplot/"; the required
> packages: zlib-1.1.4.tar.gz, libpng-1.2.5.tar.gz, and
Are you sure you need to build to build gnuplot from sources, yourself?
And that you don't want the much better GD library based PNG driver
instead of the minimal one you'll get with only libpng and zlib?
As to the error itself: that's an error in the configure script, which
nobody noticed because it doesn't strike the majority of installations
(GD-based, on Linux, using pre-installed shared libraries for libpng and