vm_trace.c: trace_func safe level check

* vm_trace.c (set_trace_func, thread_{add,set}_trace_func_m): check
  safe level as well as 1.8.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38968 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
vm_trace.c: TracePoint safe level check

* vm_trace.c (rb_tracepoint_enable, rb_tracepoint_disable): check safe
  level as well as set_trace_func.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38969 b2dd03c8-39d4-4d8f-98ff-823fe69b080e