pkg/54624: PDF export in graphics/gnuplot broken

[joern.clausen%uni-bielefeld.de@localhost]

>Number:         54624
>Category:       pkg
>Synopsis:       PDF export in graphics/gnuplot broken
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Oct 17 14:20:00 +0000 2019
>Originator:     Joern Clausen
>Release:        
>Organization:
Bielefeld University
>Environment:
>Description:
PDF export in graphics/gnuplot is completely broken. Fonts for labels are not calculated correctly, resulting in a distorted/unusable output. It's hard to describe, see examples below.

I can't find any bug upstream that seems to describe this problem, so it might be a problem in pkgsrc.
>How-To-Repeat:
Feed this to gnuplot:

set terminal pdf
set output 'gnuplot-bug.pdf'
plot sin(x)

or use

set terminal pdf font "Helvetica,8" size 28cm,20cm

It should generate warnings like

warning: Warning - difficulty fitting plot titles into key
warning: Terminal canvas area too small to hold plot.
         Check plot boundary and font sizes.

This has been tested with

gnuplot-5.2.7nb1
cairo-1.16.0

on both NetBSD 8.1 and Solaris 11.3.
>Fix: