6447715 Fix for 6405996 shatters caller's assumptions.

[dan...@sun.com]

Author: danmcd
Repository: /hg/onnv/onnv-gate
Revision: de5795df0725ba5424e34cc557adb258393a1929
Log message:
6447715 Fix for 6405996 shatters caller's assumptions.

Files:
        update: usr/src/uts/common/inet/ip/ip.c