document that silent truncation isn't a possiblity because
abort() is used as a backstop.

Notes:
Mon Sep 27 12:29:28 EDT 2010 geoff
    Not true on 386 and amd64; the manual page is correct.


Reference: /n/sources/patch/sorry/muldivman
Date: Mon Sep 27 02:13:25 CES 2010
Signed-off-by: quanstro@quanstro.net
Reviewed-by: geoff

--- /sys/man/2/muldiv	Mon Sep 27 02:13:00 2010
+++ /sys/man/2/muldiv	Mon Sep 27 02:12:59 2010
@@ -28,4 +28,8 @@
 .B long
 or
 .BR ulong ;
-on others they will silently truncate.
+on others
+.BR abort (2)
+is called to avoid slient truncation.
+.SH SOURCE
+.B /sys/src/libc/port