gfortran seems to require gcc-toolchain

[Konrad Hinsen]

Hi Guix,

I am trying to recompile old Fortran code under Guix. I made an (pure)
environment containing "gfortran" plus a few required tools (make etc.),
but found that every Fortran compilation stops with an error message
complaining about "as" missing. Installing gcc-toolchain fixes the
problem.

If gfortran cannot be used without gcc-toolchain, shouldn't
gcc-toolchain be a propagated input of gfortran?

Cheers,
  Konrad.