Fix building on systems which don't have ENODATA

This patch (a modified form of the original patch from Cyril Brulebois
<kibi@debian.org>) fixed building on systems which don't have ENODATA
(e.g.  GNU/kFreeBSD). Upstream is aware of it.

Iustin Pop, <iusty@k1024.org>
Wed, 12 Aug 2009 21:58:36 +0200
--- a/xattr.c
+++ b/xattr.c
@@ -444,7 +444,11 @@
                     }
                     nalloc = nval;
                     continue;
-                } else if(errno == ENODATA || errno == ENOATTR) {
+                } else if(
+#ifdef ENODATA
+			  errno == ENODATA ||
+#endif
+			  errno == ENOATTR) {
                     /* this attribute has gone away since we queried
                        the attribute list */
                     missing = 1;