':' and '%' have different meaning in the default sql_mode and in sql_mode=ORACLE.

To unify sql_yacc.yy and sql_yacc_ora.yy easier, we'll add sql_mode specific tokens for '%' and '%' and modify the grammar in sql_yacc.yy and sql_yacc_ora.yy accordingly.

Instead of ':' and '%', we'll have separate COLON_ORACLE_SYM and PERCENT_ORACLE_SYM.

This will make possible for the native grammar rules and Oracle grammars rules to co-exists in the same *.yy files.

By default, Lex_input_stream::lex_one_token() will return ':' and '%', and translate them to COLON_ORACLE_SYM and PERCENT_ORACLE_SYM in Oracle compatibility mode.