* parse.y (must_be_dynamic_symbol): refactoring.
  * add `inline'.
  * use UNLIKELY().
  * check only DYNAMIC_SYM_P(), otherwise it is a bug.
  * lookup_id_str() is not needed in second condition.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46693 b2dd03c8-39d4-4d8f-98ff-823fe69b080e