/usr/include/mariadb/ is in libmariadb-dev 3.0.3-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mariadb/errmsg.h
/usr/include/mariadb/ma_list.h
/usr/include/mariadb/ma_pvio.h
/usr/include/mariadb/ma_tls.h
/usr/include/mariadb/mariadb/
/usr/include/mariadb/mariadb/ma_io.h
/usr/include/mariadb/mariadb_com.h
/usr/include/mariadb/mariadb_ctype.h
/usr/include/mariadb/mariadb_dyncol.h
/usr/include/mariadb/mariadb_stmt.h
/usr/include/mariadb/mariadb_version.h
/usr/include/mariadb/mysql/
/usr/include/mariadb/mysql.h
/usr/include/mariadb/mysql/client_plugin.h
/usr/include/mariadb/mysql/plugin_auth.h
/usr/include/mariadb/mysql/plugin_auth_common.h
/usr/include/mariadb/mysqld_error.h