• mqtt: stop including mqtt_protocol.h on mosquitto 2.1+

    From Rob Swindell@1:103/705 to GitLab note in main/sbbs on Fri Sep 11 15:16:44 2026
    https://gitlab.synchro.net/main/sbbs/-/merge_requests/732#note_10330

    We don't normally include "GitLab" in references to issue numbers.
    --- SBBSecho 3.37-Linux
    * Origin: Vertrauen - [vert/cvs/bbs].synchro.net (1:103/705)