parse.y: fix lex_state after tLABEL_END

* parse.y (parser_yylex): fix lex_state after tLABEL_END, should
  be EXPR_LABELARG to be followed by "paren with arg".
  [ruby-core:66705] [Feature #4935]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48712 b2dd03c8-39d4-4d8f-98ff-823fe69b080e