thread.c: revert r38382 but deprecate rb_thread_polling()
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38391 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
thread.c: revert r38382 but deprecate rb_thread_polling()
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38391 b2dd03c8-39d4-4d8f-98ff-823fe69b080e