Depreacte libGLw and dependent ports

Deprecate graphics/libGLw, and set expiration date. libGLw has been
deprecated upstream.
Deprecate unowned and unmaintained ports that depend on libGLw:
graphics/inventor
science/xmakemol

Obtained from: FreeBSD Graphics Team development repo

		https://github.com/FreeBSDDesktop/freebsd-ports/tree/feature/libGLw-deprecate