Checking that a given variant of a port is active

[Adam Mercer]

Hi

In trying to fix #14240, scipy failing to build on Tiger using g95 as
the fortran compiler; I am wondering if its possible, in a pre-fetch
phase for example, to determine if a given variant of a specific port
is active. More precisely in the scipy ports I want to check that
numpy has been built using either the gcc42 or gcc43 variants, is this
possible and how would I go about determining this?

A bit of background information: average users of numpy itself will
probably not need the fortran aspects of numpy, i.e. f2py, therefore
for the upcoming numpy-1.1.0 (and corresponding scipy-0.7.0)
release(s) I am thinking of moving all numpy fortran support to
non-default variants. scipy however requires a numpy built using a
fortran compiler. I therefore need to ensure that numpy has been built
with either gcc42 or gcc43 fortran support prior to trying to build
scipy.

Hope that makes sense.

Cheers

Adam