How to xfail a preprocessed *.F90 file?

[Steve Kargl]

I need to xfail large_real_kind_2.F90 on amd64-*-freebsd.
The obvious change of
! { dg-do run }
to
! { dg-do run { xfail *-*-freebsd* } }
does not appear to work.

-- 
Steve