parser.c (cp_parser_nested_name_specifier_opt): Add fix-it information to diagnostic of invalid colon in nested-name-specifier.

        * parser.c (cp_parser_nested_name_specifier_opt): Add fix-it
        information to diagnostic of invalid colon in nested-name-specifier.

        * g++.dg/diagnostic/nested-name-1.C: New test.

From-SVN: r247282