cad/lepton-eda: fix build on 13.0-CURRENT

[graahnul.grom at ya.ru]

Dear committers!
  Could you please take a look at the bug report #236879
("[PATCH] cad/lepton-eda: fix build on 13.0-CURRENT") [1]?
I've submitted a patch for Lepton EDA [2] that fixes the
build more than a week ago. Successfully tested on
13.0-CURRENT r345620 amd64.
  It would be nice if I stop receiving emails from
pkg-fallout at FreeBSD.org like this [3].

[1] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=236879
[2] Lepton Electronic Design Automation:
https://github.com/lepton-eda/lepton-eda
[3]
https://lists.freebsd.org/pipermail/freebsd-pkg-fallout/Week-of-Mon-20190415/1213004.html

Regards,
Dmitry.