merge revision(s) r46465,r46469,r46484: [Backport #9961]

	* 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): 

	* vm_eval.c (rb_catch_protect): fix same problem of [Bug #9961].

	* vm_eval.c (rb_iterate): ditto.

	* vm_core.h (rb_vm_rewind_cfp): add the prototype declaration.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@47051 b2dd03c8-39d4-4d8f-98ff-823fe69b080e