[patch, libgfortran] Fix for PR 18982

[Paul Brook]

> 2005-01-17  Thomas Koenig <Thomas.Koenig@online.de>
>
>  PR libfortran/18982
>  * io/unix.c (regular_file):  No need to change flags->action
>  if an error occurs.  Document this.
>  No need to call stat() for STATUS_OLD, open() will
>  fail anyway.
>  For ACTION_UNSPECIFIED, try open for read-write, then for
>  read-only if open fails with EACCES, then for write-only
>  if that fails with EACCES again.
>  * io/unix.c (open_external): Document changed behavior of
>  regular_file.

Applied, thanks.

Paul