thread_sync.c (rb_mutex_lock): fix deadlock
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63711 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
thread_sync.c (rb_mutex_lock): fix deadlock
[ruby-core:87467] [Bug #14841]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63711 b2dd03c8-39d4-4d8f-98ff-823fe69b080e