Clang warnings: comparison of unsigned expression < 0 is always false

[yurivict]

Among other warnings, these two seem potentially damaging:

midiport.c:160:11: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        if (time < 0 || time >= info->nframes) {
            ~~~~ ^ ~
engine.c:4493:31: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
        if (req->x.port_info.port_id < 0 ||
            ~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~