iseq.c: default option

* iseq.c (rb_iseq_new_with_opt): allow NULL option as
  COMPILE_OPTION_DEFAULT.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48873 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
compile.c: constify

* compile.c (iseq_set_local_table): constify ID table.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48874 b2dd03c8-39d4-4d8f-98ff-823fe69b080e