[PATCH,fortran] Set iostat to errno on OS error

[FX Coudert]

> 2006-10-15  Steven G. Kargl  <kargl@gcc.gnu.org>
>
> 	* runtime/error.c: Add errno.h
> 	(generate_error): Set iostat to errno on OS error.
> 	* libgfortran.h: Set ERROR_OS to 5000

OK.