The website gives no indication that version 4.x is required to build
this package, and even it if were, then there should be an override in
all-packages.nix instead of referring to the 'gnumake40' attribute
directly in this expression.
New build system using configure script and GNU Make 4.0, and new
releases of the following using the new build system:
execline 2.0.0.0
s6 2.0.0.0
s6-dns 2.0.0.0
s6-linux-utils 2.0.0.0
s6-networking 2.0.0.0
s6-portable-utils 2.0.0.0
skalibs 2.0.0.0