parse.y: relax `&' warning
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57955 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
parse.y: relax `&' warning
prefix" warning when just followed by a symbol literal.
[ruby-core:79926] [Misc #13283]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57955 b2dd03c8-39d4-4d8f-98ff-823fe69b080e