thread.c: avoid inadvertent symbol creation
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40096 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
thread.c: avoid inadvertent symbol creation
(rb_thread_variable_get): ditto.
(rb_thread_key_p): ditto.
(rb_thread_variable_p): ditto.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40096 b2dd03c8-39d4-4d8f-98ff-823fe69b080e