lib/timeout.rb: fallback to Timeout::Error

* lib/timeout.rb (Timeout::ExitException.catch): pass arguments
  for new instance.
* lib/timeout.rb (Timeout::ExitException#exception): fallback to
  Timeout::Error if couldn't throw.  [ruby-dev:47872] [Bug #9380]
* lib/timeout.rb (Timeout#timeout): initialize ExitException with
  message for the fallback case.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44523 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-01-08

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44524 b2dd03c8-39d4-4d8f-98ff-823fe69b080e