[MacPorts] #64903: Libreoffice installs dependencies and then fails because it is for 10.15

[MacPorts]

#64903: Libreoffice installs dependencies and then fails because it is for 10.15
--------------------------+----------------------
  Reporter:  angelog0     |      Owner:  Tatsh
      Type:  defect       |     Status:  assigned
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:
      Port:  libreoffice  |
--------------------------+----------------------

Comment (by Tatsh):

 We would have to start doing that for so many ports. I think we should
 consider adding a `restrictions_<os_name>` global option as a function or
 boolean. So in this case

 {{{
 restrictions_darwin    ${os.major} >= 19
 }}}

 This will remove a lot of conditional code in ports. And the evaluation of
 dependencies for any package can check this field easily.

-- 
Ticket URL: <https://trac.macports.org/ticket/64903#comment:4>
MacPorts <https://www.macports.org/>
Ports system for macOS