from Thread.async_interrupt_timing to Thread.handle_interrupt,
  from Thread.async_interrupted? to Thread.pending_interrupt?.
  Also rename option from `defer' to `never'.
  [ruby-core:51074] [ruby-trunk - Feature #6762]
* vm_core.c, thread.c: rename functions and data structure
  `async_errinfo' to `pending_interrupt'.
* thread.c: add global variables sym_immediate, sym_on_blocking and
  sym_never.
* cont.c, process.c, vm.c, signal.c: ditto.
* lib/sync.rb, lib/thread.rb: catch up this renaming.
* test/ruby/test_thread.rb: ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38577 b2dd03c8-39d4-4d8f-98ff-823fe69b080e