DEPENDING ON CS

Before this fix, queries like
  SELECT * from t1
would be instrumented:
- sometime with a digest text of SELECT * from t1, and a digest hash H1
- sometime with a digest text of SELECT * from `t1`, and a digest hash H2

The root cause is in the parser, which, for the same query text t1,
returns:
- sometime an IDENT token
- sometime an IDENT_QUOTED token,
depending on both:
- whether the identifier is strictly a 7bit string or not
- whether the character set used to express the query text is multi byte or
  not

For use of digests and digest texts, such as:
- aggregation statistics by digest in the performance schema
- query match in the query rewrite plugin
- query match in the firewall plugin
the code fails to identify similar queries,
because of the difference in computed digest.

With this fix, both tokens:
- IDENT
- IDENT_QUOTED
are reduced to the same value, and printed the same way,
so that digests and digests texts are the same for similar queries.