MCOL-4936 Disable binlog for DML statements.

DML statements executed on the primary node in a ColumnStore
cluster do not need to be written to the primary's binlog. This
is due to ColumnStore's distributed storage architecture.

With this patch, we disable writing to binlog when a DML statement
(INSERT/DELETE/UPDATE/LDI/INSERT..SELECT) is performed on a ColumnStore
table. HANDLER::external_lock() calls are used to
  1. Turn OFF the OPTION_BIN_LOG flag
  2. Turn ON the OPTION_BIN_TMP_LOG_OFF flag
in THD::variables.option_bits during a WRITE lock call.

THD::variables.option_bits is restored back to the original state
during the UNLOCK call in HANDLER::external_lock().

Further, isDMLStatement() function is added to reduce code verbosity
to check if a given statement is a DML statement.

Note that with this patch, not writing to primary's binlog means
DML replication from a ColumnStore cluster to another ColumnStore
cluster or to another foreign engine will not work.

dbcon/mysql/ha_mcs_impl_if.h

@@ -444,6 +444,15 @@ inline bool isUpdateOrDeleteStatement(const enum_sql_command& command)
         isDeleteStatement(command);
 }
 
+inline bool isDMLStatement(const enum_sql_command& command)
+{
+    return (command == SQLCOM_INSERT ||
+        command == SQLCOM_INSERT_SELECT ||
+        command == SQLCOM_TRUNCATE ||
+        command == SQLCOM_LOAD ||
+        isUpdateOrDeleteStatement(command));
+}
+
 #ifdef DEBUG_WALK_COND
 void debug_walk(const Item* item, void* arg);
 #endif