Log Message:
Rather than use a separate install script, move the installation code into the
Makefile (like usual).  As part of this, we can now use the various INSTALL_*
definitions instead of the hard-coded ones in the script.

The only functional change is that all the files are now installed with Pkgsrc
default ownership, instead of hard-coded "bin:bin".  However, this \ 
does mean
that non-root installation can now work, which is a good thing.