iseq.c: use lvar index

* iseq.c (iseq_data_to_ary): use local variable indexes for hidden
  variable instead of meaningless ID values.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48679 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
compile.c: set true and false directly

* compile.c (iseq_set_arguments): directly set true and false
  default values not only nil to keyword arguments.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48680 b2dd03c8-39d4-4d8f-98ff-823fe69b080e