Ruby

• thread_pthread.c (add_signal_thread_list): use xmalloc instead
  of malloc.
• thread_pthread.c (remove_signal_thread_list): use xfree instead
  of free.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@31474 b2dd03c8-39d4-4d8f-98ff-823fe69b080e