* refactor: move `irep_remove_lv` from `mruby-bin-strip` gem to src/dump and rename to `mrb_irep_remove_lv`
* add: mrbc option `--remove-lv` to remove LVAR section
No need to optimize since a program only exits once and errors are rare.
Also the mruby source code doesn't have these kind of checks elsewhere.
The ones in {Time,Random}#initialize are kept because there it actually
matters
since initialization always happens and re-initialization is unlikely.
KOBAYASHI Shuji