* thread.c: Grammar for #backtrace_locations and ::handle_interrupt


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39460 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* thread.c: Document ThreadGroup::Default


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39461 b2dd03c8-39d4-4d8f-98ff-823fe69b080e