Fix command line option decoding

Fix command line option decoding

LVM has huge set of options now - it's approaching 60 short-arg less options
and we get interesting case of misdetection for 'merge' option which has been
put into the middle of options with 'short_arg' - thus certainly past 65. (ASCII 'A').

To avoid confusion of short_arg with long_opt number - add  '128' to all such
non-short-arg options.