Don't stop traversing a directory hierarchy if we reach SHRT_MAX,

just stop updating fts_level so we don't overflow it.  This allows
rm, find, etc to operate on very deep hierarchies.  Consumers of
fts(3) do need to be aware that the actual level may be larger
than fts_level.  During the next libc major bump we will make
fts_level an int instead of a short.  OK deraadt@

src/include/fts.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: fts.h,v 1.11 2005/06/17 20:36:55 millert Exp $	*/
+/*	$OpenBSD: fts.h,v 1.12 2009/08/27 16:19:27 millert Exp $	*/
 /*	$NetBSD: fts.h,v 1.5 1994/12/28 01:41:50 mycroft Exp $	*/
 
 /*
@@ -79,6 +79,7 @@ typedef struct _ftsent {
 
 #define	FTS_ROOTPARENTLEVEL	-1
 #define	FTS_ROOTLEVEL		 0
+#define	FTS_MAXLEVEL		 0x7fff
 	short fts_level;		/* depth (-1 to N) */
 
 #define	FTS_D		 1		/* preorder directory */