deceit operations for clans+chiefs.

[Daniel Potts]

Assume task A is the chief of task B, which is the chief of task C, which
is the chief of task D. ;-)

* Now, D does an ipc call to A. A successfully receives the message from D
via the chiefs (C and B). 

* Now when A replies to this, the message first gets intercepted by B. 

* B sends a deceiting ipc to D with A as the virtual sender. This gets
intercepted by C.

* C sends a deceiting ipc to D with A as the virtual sender. This step
fails (?!) due to direction preservation not holding. That is when C 
checks nchief on A it returns L4_NC_OUTER_CLAN, and nchief on D returns
L4_NC_SAME_CLAN, which is not equal, and therefore not direction
preserving.

Have I got this scenario correct? Assuming that each cheif can obtain the
virtual sender as part of it's ipc api.

Cheers,

Daniel