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/qc_sqlite/qc_sqlite.cc

@@ -514,6 +514,8 @@ public:
     {
         ss_dassert(zColumn);
 
+        // NOTE: This must be first, so that the type mask is properly updated
+        // NOTE: in case zColumn is "currval" etc.
         if (is_sequence_related_field(zDatabase, zTable, zColumn))
         {
             m_type_mask |= QUERY_TYPE_WRITE;
@@ -527,6 +529,19 @@ public:
             return;
         }
 
+        if (!zDatabase && zTable)
+        {
+            Aliases::const_iterator i = m_aliases.find(zTable);
+
+            if (i != m_aliases.end())
+            {
+                const QcAliasValue& value = i->second;
+
+                zDatabase = value.zDatabase;
+                zTable = value.zTable;
+            }
+        }
+
         QC_FIELD_INFO item = { (char*)zDatabase, (char*)zTable, (char*)zColumn, usage };
 
         size_t i;