rx: Check for peer deadness in rxi_Resend

rx: Check for peer deadness in rxi_Resend

If we need to resend something, the peer we're sending to may be dead.
Check if the peer is dead in rxi_Resend, so we don't have to wait
(possibly several seconds) for the next rxi_CheckCall.

Change-Id: I0ecc0b1fc23bb4194ebadcea97dd58c938af8154
Reviewed-on: http://gerrit.openafs.org/8118
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>