* parse.y: change Symbol <-> ID relationship to avoid
  exposing IDs from collectable symbols.
  [Bug #10014]
  Now, rb_check_id() returns 0 if corresponding symbol is
  pinned dynamic symbol.
  There is remaining intern_cstr_without_pindown(), it can return
  IDs from collectable symbols. We must be careful to use it
  (only used in parse.y).  I think it should be removed if
  it does not have impact for performance.
* parse.y:
  add:
  * STATIC_SYM2ID()
  * STATIC_ID2SYM()
  rename:
  * rb_pin_dynamic_symbol() -> dsymbol_pindown()
* internal.h:
  remove:
  * rb_check_id_without_pindown()
  * rb_sym2id_without_pindown()
  add:
  * rb_check_symbol()
  * rb_check_symbol_cstr()
* load.c: use rb_check_id() or rb_check_id_cstr().
* object.c: ditto.
* struct.c: ditto.
* thread.c: ditto.
* vm_method.c: ditto.
* string.c (sym_find): use only rb_check_symbol().
* sprintf.c (rb_str_format): use rb_check_symbol_cstr().



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46764 b2dd03c8-39d4-4d8f-98ff-823fe69b080e