- Apply the patch from pkg/13188 by Ron Roskens <roskens@elfin.net> to
fix problems with hard-coding /var/amanda.
- Remove USE_X11 from amanda-server since amanda-plot has already been
split out.
- Don't explicitly look for headers in ${PREFIX}/include.
Add a new USE_LIBTOOL definition that uses the libtool package instead of
pkglibtool which is now considered outdated.
USE_PKGLIBTOOL is available for backwards compatibility with old packages
but is deprecated for new packages.
