journal-remote: set a limit on the number of fields in a message

journal-remote: set a limit on the number of fields in a message

Existing use of E2BIG is replaced with ENOBUFS (entry too long), and E2BIG is
reused for the new error condition (too many fields).

This matches the change done for systemd-journald, hence forming the second
part of the fix for CVE-2018-16865
(https://bugzilla.redhat.com/show_bug.cgi?id=1653861).

(cherry picked from commit ef4d6abe7c7fab6cbff975b32e76b09feee56074)
(cherry picked from commit 1c9232336460d0f004156964df1478e4d3ddac97)

Gbp-Pq: Name journal-remote-set-a-limit-on-the-number-of-fields-in-a-m.patch