* vm.c (rb_vm_rewind_cfp): add new function to rewind specified cfp
  with invoking RUBY_EVENT_C_RETURN.
  [Bug #9961]
* vm_core.h: ditto.
* eval.c (rb_protect): use it.
* eval.c (rb_rescue2): ditto.
* vm_eval.c (rb_iterate): ditto.
* test/ruby/test_settracefunc.rb: add a test.
* vm_core.h (rb_name_err_mesg_new):



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46465 b2dd03c8-39d4-4d8f-98ff-823fe69b080e