engine/schema: fix upgrade path to work with MySQL 5.7

Found this issue when using MySQL 5.7 with Ubuntu 16.04 with following settings:

sql-mode="STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION,ERROR_FOR_DIVISION_BY_ZERO,NO_ZERO_DATE,NO_ZERO_IN_DATE,NO_ENGINE_SUBSTITUTION"
server-id   = 1
innodb_rollback_on_timeout=1
innodb_lock_wait_timeout=600
max_connections=350
log-bin=mysql-bin
binlog-format = 'ROW'

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

Author: yadvr

engine/schema/src/com/cloud/upgrade/dao/Upgrade410to420.java

@@ -1297,7 +1297,7 @@ private void addHostDetailsIndex(Connection conn) {
                     s_logger.debug("Index already exists on host_details - not adding new one");
                 } else {
                     // add the index
-                    try(PreparedStatement pstmtUpdate = conn.prepareStatement("ALTER IGNORE TABLE `cloud`.`host_details` ADD INDEX `fk_host_details__host_id` (`host_id`)");) {
+                    try(PreparedStatement pstmtUpdate = conn.prepareStatement("ALTER TABLE `cloud`.`host_details` ADD INDEX `fk_host_details__host_id` (`host_id`)");) {
                         pstmtUpdate.executeUpdate();
                         s_logger.debug("Index did not exist on host_details -  added new one");
                     }catch (SQLException e) {