[HEADS UP] USE_FORTRAN knob has been added

[Maho NAKATA]

Hi
after discussions and tests, now we are able to use USE_FORTRAN
knob.

All the ports that use FORTRAN should use this knob.
USE_FORTRAN=yes (gfortran42)
USE_FORTRAN=ifort (intel fortran compiler)
USE_FORTRAN=g77  (/usr/bin/f77;FBSD<=6 or g77-34; FBSD>=7)

Thanks,
-- Nakata Maho (maho at FreeBSD.org)