vm_eval.c: refine messages
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51742 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
vm_eval.c: refine messages
symbol is not given. [Fix GH-1013]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51742 b2dd03c8-39d4-4d8f-98ff-823fe69b080e