* struct.c (rb_struct_set, rb_struct_aref, rb_struct_aset): get
rid of pinning down dynamic symbols by SYM2ID.
* struct.c (rb_struct_aref_sym, rb_struct_aset_sym): use Symbol
instead of ID.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45465 b2dd03c8-39d4-4d8f-98ff-823fe69b080e