Update the hc-build script to the recipe I'm using for the FreeBSD
package build.  The main improvement is that after running this script
the resulting tree should be ready for a 'make install' from the top
level.  This is highly fragile and relies on touching various files to
avoid having to recompile anything that will fail :-)

The FreeBSD package that this derives from is well tested, but I
haven't tested the script itself yet.