/usr/include/php5/ext/mysqlnd_ms/ is in php5-mysqlnd-ms 1.6.0-1+b1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/php5/ext/mysqlnd_ms/config.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_config_json.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_enum_n_def.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_filter_groups.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_filter_qos.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_filter_random.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_filter_round_robin.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_filter_table_partition.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_filter_user.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_lb_weights.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_ms_switch.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_qp.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_query_lexer.lex.h
/usr/include/php5/ext/mysqlnd_ms/mysqlnd_query_parser.h
/usr/include/php5/ext/mysqlnd_ms/php_mysqlnd_ms.h