MXS-3041 Fix 'SELECT handler FROM t FOR UPDATE'

Problem was that 'handler' is a keyword. To make it work,
the keyword must be listed as one of those that turns into
an id where it cannot be used as a keyword.

query_classifier/qc_sqlite/sqlite-src-3110100/src/parse.y

@@ -625,6 +625,7 @@ columnid(A) ::= nm(X). {
   /*EACH*/ END ENGINE ENUM EXCLUSIVE /*EXPLAIN*/ EXTENDED
   FIELDS FIRST FLUSH /*FOR*/ FORMAT
   GLOBAL
+  HANDLER
   // TODO: IF is a reserved word and should not automatically convert into an identifer.
   IF IMMEDIATE INITIALLY INSTEAD
   /*KEY*/