graphviz, graphviz-devel: Add port:flex build dependency

[michaelld (Michael Dickens)]

graphviz checks for flex, and uses the system version (/usr/bin/flex) if found. If the flex port is installed, it will use that -- but, flex is not listed as a build dependency. At least on some systems (per a customer support issue I was handling for GNU Radio), the system flex fails to property generate output, causing graphviz to fail to configure. Moving to using MacPorts' flex solves this issue. Hence, adding in port:flex as a build dependency seems like the way to go.

[ryandesign (Ryan Carsten Schmidt)]

I've no objection to that, we would just need to figure out which of the (sub)ports need that dependency.

[ryandesign (Ryan Carsten Schmidt)]

Has duplicate #58457.

[ryandesign (Ryan Carsten Schmidt)]

Sorry, I was wrong. #58457 was not a duplicate.

I have not seen a failure building the graphviz ports with macOS flex. And indeed some users have reported problems building graphviz and other MacPorts software when using MacPorts flex; #58457 is one such instance. Other tickets point at possible conflicting files installed by Homebrew being the cause of the problem, but I don't think we've ever gotten a definitive analysis and solution.

So I don't feel that adding a flex dependency would help this port.

[Smattr (Matthew Fernandez)]

For some further context, Graphviz did actually make some changes that briefly broke building with the default macOS Flex. But I believe these never made it into a release before we reverted them. The sad sob story: ​https://gitlab.com/graphviz/graphviz/-/commit/b64593afc07d3f62a13a3b6b634bcb80b7fe6180

[mascguy (Christopher Nielsen)]

Since we're in the process of updating graphviz, the $100,000 question is: Should we add a build dep for flex? If not, this ticket can be closed as "won't fix."

[mascguy (Christopher Nielsen)]

Since our updated graphviz port is building across-the-board on our buildbots, I'm closing this. If we need to revisit at some point, we can certainly do so.