deprecated.maximum_osmajor vs. checking os.major in Portfile

[Christopher Chavez]

I would like to mark the DesktopManager port as deprecated due to no upstream support. The Portfile currently checks ${os.major} for an exact version. Should specifying `deprecated.maximum_osmajor` be avoided due to being redundant?

Conversely, for ports that can be deprecated but are checking `${os.major}` as a maximum version (rather than a minimum or exact), if they were to use `deprecated.maximum_osmajor` should they then not be checking `${os.major}`?

Christopher A. Chavez