Mac-only package use of xcodebuild?

[Jan Danielsson <jan.m.danielsson%gmail.com@localhost>]

Hello,

   As Enigmail is moving to only support gpg2, I decided to give it a
try on my Mac.  I encountered plenty of problems, which I will not go
through here, but one of the really annoying issue was that it told me
that a (sub)key had expired (the key worked fine with gpg 1.x).  The
problem actually turned out to be that it couldn't run the configured
pinentry program.  (Very helpful error message).

   I worked around it by installing MacGPG2 and using its pinentry-mac,
but I would prefer to have to install MacGPG2.  It looks like the
pinentry-mac program is a stand-alone project on github and as such
could "easily" be made into a package, but its makefile runs xcodebuild
to build the binary.

   What is the proper way to import such packages?  Are there any prior
cases where project makefiles call platform-specific build tools?  Or is
it expected that one writes a new build system which honors the pkgsrc
tools?

-- 
Kind Regards,
Jan