Comment out info on U (utrace) malloc option since we don't support it

on OpenBSD.

src/lib/libc/stdlib/malloc.3

@@ -34,7 +34,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: malloc.3,v 1.22 2001/10/30 21:17:44 tdeval Exp $
+.\"	$OpenBSD: malloc.3,v 1.23 2001/11/05 21:31:21 millert Exp $
 .\"
 .Dd August 27, 1996
 .Dt MALLOC 3
@@ -208,13 +208,13 @@ Always reallocate when
 .Fn realloc
 is called, even if the initial allocation was big enough.
 This can substantially aid in compacting memory.
-.Pp
-.It Cm U
-.Dq utrace .
-Generate entries for
-.Xr ktrace 1
-for all operations.
-Consult the source for this one.
+.\".Pp
+.\".It Cm U
+.\".Dq utrace .
+.\"Generate entries for
+.\".Xr ktrace 1
+.\"for all operations.
+.\"Consult the source for this one.
 .Pp
 .It Cm X
 .Dq xmalloc .