[RFHC] _XOPEN_SOURCE and OpenBSD 3.9

[RFHC] _XOPEN_SOURCE and OpenBSD 3.9

[Junio C Hamano]

I was futzing with an OpenBSD 3.9 bochs today, and it appears
that without __BSD_VISIBILITY we get a complaint from the
compiler that says S_ISLNK() is implicitly declared function
(cache.h has an inline create_ce_mode() that uses this macro).

I do not think this breaks things on Linux boxes, but I do not
have access to other archs, hence this request for help and
comments.

Jason Riedy CC'ed who did the initial _XOPEN_SOURCE=500 for AIX
portability.

Oh, yes, I know OpenBSD 4.0 is very soon coming...

diff --git a/convert-objects.c b/convert-objects.c
index 631678b..2ff19d2 100644
--- a/convert-objects.c
+++ b/convert-objects.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE 500 /* glibc2 and AIX 5.3L need this */
+#define _XOPEN_SOURCE 600 /* glibc2 and AIX 5.3L need 500; 600 for OBSD */
 #define _XOPEN_SOURCE_EXTENDED 1 /* AIX 5.3L needs this */
 #define _GNU_SOURCE
 #include <time.h>