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: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@redhat.com>