The libgfortran configure sets FC to be $GFORTRAN. We did used to patch
that out but rather than carry a patch to gcc, just set GFORTRAN as
needed.
(From OE-Core rev: 4ec096a9ce8a49b631efc50e7d95ff653d4c4374)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>