Update yacc_sql.y

[evtrouble]

Fix memory leak of token when bison failed to parse SQL.
Use left recursion for better performance and remove vector reverse.

What problem were solved in this pull request?

When bison fails to parse SQL, memory leaks may occur, such as
select * from t where id><1;

Issue Number: close #308

Problem:

What is changed and how it works?

In yacc_sql.y, use %destructor to specify the memory release action that needs to be called when parsing fails for the token, in order to prevent memory leaks that may occur in the event of an error.

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