MXS-1340 Report true table and not alias name

With this change, for a statement like

    SELECT t2.a FROM t1 t2;

the affected field is reported as t1.a and not as t2.a, as it
was before.

For a statement like

    SELECT t.f FROM d.t;

qc_mysqlembedded will now return "d.t.f" as the affected field,
while qc_sqlite will still return "t.f" as both implementations did
before. In qc_mysqlembedded's case that is a side-effect of the
alias handling. To get qc_sqlite to return the same (which would
be good), the table names would have to be collected in a smarter
way than they are now.

query_classifier/test/qc_sqlite_unsupported.test

@@ -57,3 +57,10 @@ SELECT LENGTH(_utf8 0xC39F), LENGTH(CHAR(14844588 USING utf8));
 # warning: [qc_sqlite] Statement was classified only based on keywords
 # (Sqlite3 error: SQL logic error or missing database, near "0xC39F": syntax error):
 # "SELECT LENGTH(_utf8 0xC39F), LENGTH(CHAR(14844588 USING utf8));"
+
+SELECT t.f FROM d.t;
+# qc_get_field_info        : ERR: d.t.f(QC_USED_IN_SELECT) != t.f(QC_USED_IN_SELECT)
+# Table names need to be collected in a more intelligent fashion to be able
+# to do that.
+select t.c,t1.b from t,mysqltest.t1 where t.c=t1.a;
+with t as (select c from mysqltest.t2 where c < 2) select t.c,t1.b from t,mysqltest.t1 where t.c=t1.a;