Log Message:
net/netatalk4: Specify path to service(8) tool on NetBSD.

This is a kind of silly hack -- the build does not actually run
service(8) at build-time, but it searches for a path, which must
exist at build-time, to a command by that name, if we don't specify a
path via meson binaries.  If it can't find the path and we don't
specify one, it disables the rc.d script generation.  We don't even
really have to put /usr/sbin/service here; we could put /quagga/eland
instead and I think it doesn't change anything in the build output.

Resolves the following symptom when /usr/sbin is not in PATH during
the build (or, in principle, when you're cross-building for NetBSD
from non-NetBSD):

===> Building for netatalk-4.0.6nb5
...
Writing index.html for book(netatalk-manual)
*** Please use pkgtools/verifypc to sanity check dependencies.
bmake[1]: don't know how to make \ 
/home/riastradh/pkgsrc/current/work/net/netatalk4/work/netatalk-netatalk-4-0-6/output/distrib/initscripts/netatalk. \ 
Stop

bmake[1]: stopped in /home/riastradh/pkgsrc/current/pkgsrc/net/netatalk4
*** Error code 2