Ruby

• vm_trace.c: separate trace_func related functions from
  thread.c.
• thread.c: ditto.
• common.mk: add vm_trace.o.
• inits.c: call Init_vm_trace().

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36703 b2dd03c8-39d4-4d8f-98ff-823fe69b080e