signal.c: directly enqueue

* signal.c (rb_f_kill): directly enqueue an ignored signal to self,
  except for SIGSEGV and SIGBUS.  [ruby-dev:48203] [Bug #9820]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45911 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
thread.c: always deliver signal immediately

* thread.c (ruby_kill): always deliver signal immediately, without
  check for main thread.  no longer called in other context.
  [ruby-dev:48203] [Bug #9820]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45912 b2dd03c8-39d4-4d8f-98ff-823fe69b080e