[gfortran] patch for unlink on open files

[FX Coudert]

> Is there any particular reason you're doing the unpack early?
> As opposed to one hunk
> 
> #if !HAVE_UNLINK_OPEN_FILE
>   if (u->flags.status == STATUS_SCRATCH || status == CLOSE_DELETE)
>     {
>       char *path = (char *) alloca (u->file_len + 1);
>       unpack_filename (path, u->file, u->file_len);
>       unlink (path);
>     }
> #endif

The unlink has to be done after the call to close_unit(u), but the call 
frees the memory allocated to u. So, we need to unpack (that will store 
the filename), close the unit and then unlink.

FX