libf2c declaration tweak

[Dave Love]

The definition is necessary with glibc2 to get a prototype (since we
define _POSIX_SOURCE) now that tempnam gets used again.  A candidate
for the release branch?

1998-10-08  Dave Love  <fx@gnu.org>

	* libI77/open.c (_XOPEN_SOURCE): Define for tempnam's sake.

Index: open.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/libf2c/libI77/open.c,v
retrieving revision 1.4
diff -p -c -r1.4 open.c
*** open.c	1998/09/30 02:45:44	1.4
--- open.c	1998/10/08 23:07:36
***************
*** 1,3 ****
--- 1,4 ----
+ #define _XOPEN_SOURCE 1		/* for tempnam with glibc */
  #include "f2c.h"
  #include "fio.h"
  #include <string.h>