Ruby

• thread.c (rb_mutex_lock): moved trap context check from
  rb_mutex_trylock because try_lock have no change to make
  a deadlock.
• thread.c (rb_mutex_trylock): ditto.
• NEWS: news for the above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37922 b2dd03c8-39d4-4d8f-98ff-823fe69b080e