* safe.c (rb_set_safe_level): call `rb_vm_stack_to_heap()`
  to set block parameter.

* safe.c (rb_set_safe_level): use `GET_EC()`.

* safe.c (safe_setter): ditto.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60563 b2dd03c8-39d4-4d8f-98ff-823fe69b080e