[PATCH] Fortran: allow NULL() for POINTER, OPTIONAL, CONTIGUOUS dummy [PR111503]

[FX Coudert]

Hi Harald,

> here's another fix for the CONTIGUOUS attribute: NULL() should
> derive its characteristics from its MOLD argument; otherwise it is
> "determined by the entity with which the reference is associated".
> (F2018:16.9.144).

Looking good to me, but leave 48 hours for someone else to object if they want.

Best,
FX