rx: RX_CALL_IDLE and RX_CALL_BUSY

rx: RX_CALL_IDLE and RX_CALL_BUSY

Allocate new Rx error codes for Idle and Busy calls but do not
send these errors on the wire.  They are only intended for local
use.

RX_CALL_IDLE is an indication to an application that requests it
that the rx peer is maintaining an open call channel but has not
sent any actual data for the length of the registered idle dead
timeout.

RX_CALL_BUSY is an indication to an application that requests it
that the rx peer believes the selected call channel is in use by
a pre-existing call.

When either RX_CALL_IDLE or RX_CALL_BUSY are assigned as the call
error and an abort must be sent to the rx peer, the errors are
translated to RX_CALL_TIMEOUT.  This is necessary because it is
not possible to add new Rx error values in a method that is safe
for peers that are not expecting them.

This patchset also documents which Rx errors defined in rx.h are
used on the wire and which are not.

The Unix and Windows cache managers are updated to build with
these new error codes.

Change-Id: Ib236f27b88d503c68134534bb069e12dd83537d8
Reviewed-on: http://gerrit.openafs.org/6128
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>