imapc: Use SHA1 of message header for guid-forced instead of the entire body.
imapc: Use SHA1 of message header for guid-forced instead of the entire body.

jwm/dovecot-notmuch,jkerihuel/dovecot,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jkerihuel/dovecot,jwm/dovecot-notmuch,jkerihuel/dovecot,jkerihuel/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch