rb_thread_start_timer_thread()): added.
* thread_pthread.ci: add a native_thread_join() and move
rb_thread_reset_timer_thread() definition to thread.c.
* thread_win32.ci: ditto
* process.c: fix before_exec(), after_exec() to stop timer thread
(and restart timer thread if exec failed). and fix to reset
timer thread information when forked child process starts
(to fix [ruby-core:09822]).
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@11509 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
