MXS-3121 Expose statement currently being classified

Intended to be used from fatal signal handlers. As the statement will
be returned only while classification is in process, if a statement
is returned, it is an indication that the crash was caused by the
classification.

query_classifier/qc_sqlite/qc_sqlite.cc

@@ -5359,6 +5359,20 @@ int32_t qc_sqlite_set_options(uint32_t options)
     return rv;
 }
 
+int32_t qc_sqlite_get_current_stmt(const char** ppStmt, size_t* pLen)
+{
+    int32_t rv = QC_RESULT_ERROR;
+
+    if (this_thread.pInfo && this_thread.pInfo->m_pQuery && (this_thread.pInfo->m_nQuery != 0))
+    {
+        *ppStmt = this_thread.pInfo->m_pQuery;
+        *pLen = this_thread.pInfo->m_nQuery;
+        rv = QC_RESULT_OK;
+    }
+
+    return rv;
+}
+
 /**
  * EXPORTS
  */
@@ -5395,7 +5409,8 @@ extern "C"
             qc_sqlite_info_dup,
             qc_sqlite_info_close,
             qc_sqlite_get_options,
-            qc_sqlite_set_options
+            qc_sqlite_set_options,
+            qc_sqlite_get_current_stmt
         };
 
         static MXS_MODULE info =