* lib/timeout.rb (Timeout#timeout): when a custom exception is given,
no instance is needed to be caught, so defer creating new instance
until it is raised. [ruby-core:59511] [Bug #9354]
* lib/timeout.rb (Timeout#timeout): should not rescue ordinarily
raised ExitException, which should not be thrown.
* lib/timeout.rb (Timeout::ExitException.catch): set @thread only if
it ought to be caught.
* 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.
merge revision(s) 44517,44518,44519,44523: [Backport #9354]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@44841 b2dd03c8-39d4-4d8f-98ff-823fe69b080e