* include/ruby/ruby.h: add old macro name `RUBY_EVENT_SWITCH'.
  This macro name is obsolete because it is renamed to
  RUBY_INTERNAL_EVENT_SWITCH, but it has compatibility problem
  using this macro name like ruby-prof.
  I want to remove this macro after ruby 2.1.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42441 b2dd03c8-39d4-4d8f-98ff-823fe69b080e