The virtual is intended to be used for portable packages, along with portability.eclass' get_bmake function.
1. fix your package to use get_bmake, if it can work with any form of BSD-like make,
2. fix your package to depend on sys-devel/pmake directly.
However, note that sys-devel/pmake is dead and going to be lastrited soonish in favor of sys-devel/bmake.
I've changed the dep to unblock fixing virtual/pmake. Please decide whether you're happy with it as-is, or test it with bmake and if it works, update the ebuild to use get_bmake and the virtual.
Author: Michał Górny <firstname.lastname@example.org>
AuthorDate: Sat Jun 24 12:24:11 2017
Commit: Michał Górny <email@example.com>
CommitDate: Sat Jun 24 12:36:58 2017
net-analyzer/symon: Dep on sys-devel/pmake, #622598