normalize reference to Timeout::Error

From: John Bachir <j@jjb.cc>

* bootstraptest/test_io.rb (assert_finish):
  normalize rescue for Timeout::Error
* lib/net/ftp.rb (Net#read_timeout): ditto for doc
* lib/resolv.rb (Resolv::ResolvTimeout): ditto for subclass
* lib/webrick/httprequest.rb (_read_data): ditto for rescue
* sample/timeout.rb (p timeout): ditto for call
* test/drb/drbtest.rb (test_06_timeout): ditto
* test/ruby/test_readpartial.rb (test_open_pipe): ditto
* test/thread/test_queue.rb (test_queue_thread_raise): ditto
* thread.c (rb_thread_s_handle_interrupt): ditto for doc
  [ruby-core:65481] [misc #10339]

TimeoutError is a legacy constant, Timeout::Error is the canonical constant.
This patch normalizes all code and comments to reference Timeout::Error.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47838 b2dd03c8-39d4-4d8f-98ff-823fe69b080e