iseq.c: remove unused rb_iseq_new_with_bopt

* iseq.c (prepare_iseq_build): remove unused block_opt param
  (rb_iseq_new_with_bopt_and_opt): remove
  (rb_iseq_new_with_opt): inline removed function
  (rb_iseq_new_with_bopt): remove
  (iseq_load): adjust prepare_iseq_build call
  [Feature #10565]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48713 b2dd03c8-39d4-4d8f-98ff-823fe69b080e