afs: Fix client call Rx-phase signal handling

commit 7d7587db0d7fd1138f2afcffdc46a8e15630b944 upstream.

Fix the handling of signals in client rxrpc calls made by the afs
filesystem.  Ignore signals completely, leaving call abandonment or
connection loss to be detected by timeouts inside AF_RXRPC.

Allowing a filesystem call to be interrupted after the entire request has
been transmitted and an abort sent means that the server may or may not
have done the action - and we don't know.  It may even be worse than that
for older servers.

Fixes: bc5e3a54 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>