avoid inadvertent symbol creation in reflection methods. based
on a patch by Jeremy Evans at [ruby-core:38367]. [Feature #5072]
* vm_method.c (rb_mod_method_defined)
(rb_mod_{public,private,protected}_method_defined)
(obj_respond_to): ditto.
* parse.y (rb_check_id): new function returns already interned ID
or 0.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32621 b2dd03c8-39d4-4d8f-98ff-823fe69b080e