misc: avoid some dead initialization warnings

misc: avoid some dead initialization warnings

Clang analyzer warnings:

Dead store, Dead initialization:

    lib/mbsedit.c:154:8: warning: Value stored to 'in' during its initialization is never read
            char *in = (char *) &c;
                  ^~   ~~~~~~~~~~~

    misc-utils/findmnt-verify.c:129:14: warning: Value stored to 'cn' during its initialization is never read
            const char *cn = tgt;
                        ^~   ~~~
Dead store, Dead increment:

    sys-utils/hwclock.c:1461:2: warning: Value stored to 'argv' is never read
            argv += optind;
            ^       ~~~~~~

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>