remove Perl build dependency
As best I can tell, building Graphviz currently requires Perl for a single thing: running lib/common/mksvgfonts.pl. Looking at this script and how it is run, I have the impression Perl is not necessary. Going further, I would say a script is not necessary. This can probably be accomplished with a regular header or, if not that simple, an X macro.
Making this change would allow us to drop Perl as a build dependency, delete Perl from the Windows build dependency repo, and generally exit the Perl game altogether.
Interestingly the MSBuild system does not run this script, suggesting it is not necessary on Windows. Though the CMake build system on Windows does run the script.