[MacPorts] #49128: Fix description of gfortran variant in compilers PortGroup

[MacPorts]

#49128: Fix description of gfortran variant in compilers PortGroup
-----------------------------+---------------------------------
 Reporter:  davide.liessi@…  |      Owner:  macports-tickets@…
     Type:  defect           |     Status:  new
 Priority:  Normal           |  Milestone:
Component:  ports            |    Version:
 Keywords:  haspatch         |       Port:  compilers-PortGroup
-----------------------------+---------------------------------
 The description of the variant didn't match the current
 `compilers.gcc_default`.
 With this patch the description changes automatically as the value of that
 variable is changed.

 (I'm putting Sean in CC because the patch is related to changes he made.)

-- 
Ticket URL: <https://trac.macports.org/ticket/49128>
MacPorts <https://www.macports.org/>
Ports system for OS X