Introduce an option "--dump=insns_without_opt" for debugging purposes

[mame]

$ ./miniruby --dump=insns -e '1 =~ 2'
== disasm: #<ISeq:<main>@-e:1 (1,0)-(1,6)> (catch: FALSE)
0000 putobject_INT2FIX_1_                                             (   1)[Li]
0001 putobject                              2
0003 opt_regexpmatch2                       <calldata!mid:=~, argc:1, ARGS_SIMPLE>[CcCr]
0005 leave

$ ./miniruby --dump=insns_without_opt -e '1 =~ 2'
== disasm: #<ISeq:<main>@-e:1 (1,0)-(1,6)> (catch: FALSE)
0000 putobject                              1                         (   1)[Li]
0002 putobject                              2
0004 send                                   <calldata!mid:=~, argc:1, ARGS_SIMPLE>, nil
0007 leave