[PATCH] Connect stderr to Unit 0 (PR libgfortran/19052)

[Paul Brook]

>  * libgfortran.h (options_t): Add stderr_unit.
>  * io/unit.c (init_units): Initialize stderr_unit.
>  * io/unix.c (error_stream): New function.
>  * runtime/environ.c (GFORTRAN_STDERR_UNIT): New environment variable.

Ok.

> + stream *
> + error_stream (void)
> + {
> +

Stray blank line here.

Paul