Low: daemons,libcrmcommon: send status code with client acks

The daemons ack client requests in many circumstances. Previously, this did not
include any sort of status. Now, it does (an exit status, since those are
guaranteed to be host-independent).

I went with CRM_EX_INDETERMINATE for async acks (i.e. result is not known at
ack time), CRM_EX_INVALID_PARAM for unrecognized commands, and CRM_EX_PROTOCOL
for inability to extract IPC data.

This also gets rid of a couple of unnecessary checks for
crm_ipc_client_response (the ack function already checks for it).