> Isn't this what mtree is for ?

Perhaps.  It would be useful then if the top level Makefile used it.

Personally I prefer my approach as it is more generally useful.

The bsd.*.mk macros are great for building UNIX, but to a large extent
useless for anything else as they require all installing to be done by
root (due to the fact that the install rules always use -o and -g).

I've been using modified versions of these macros for general s/w
building on a number of platforms for some time and really like the
ease with which one can do multi-platform building.

I've submitted changes in the past to remove the make install need for
root, but they haven't made it into the tree (yet).

--sjg