/usr/include/xmms2/xmms/ is in xmms2-dev 0.8+dfsg-18.1build3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/xmms2/xmms/xmms_bindata.h
/usr/include/xmms2/xmms/xmms_config.h
/usr/include/xmms2/xmms/xmms_error.h
/usr/include/xmms2/xmms/xmms_ipc.h
/usr/include/xmms2/xmms/xmms_log.h
/usr/include/xmms2/xmms/xmms_medialib.h
/usr/include/xmms2/xmms/xmms_object.h
/usr/include/xmms2/xmms/xmms_outputplugin.h
/usr/include/xmms2/xmms/xmms_plugin.h
/usr/include/xmms2/xmms/xmms_sample.h
/usr/include/xmms2/xmms/xmms_streamtype.h
/usr/include/xmms2/xmms/xmms_util.h
/usr/include/xmms2/xmms/xmms_xformplugin.h
/usr/include/xmms2/xmmsc/xmmsc_compiler.h
/usr/include/xmms2/xmmsc/xmmsc_errorcodes.h
/usr/include/xmms2/xmmsc/xmmsc_idnumbers.h
/usr/include/xmms2/xmmsc/xmmsc_ipc_msg.h
/usr/include/xmms2/xmmsc/xmmsc_ipc_transport.h
/usr/include/xmms2/xmmsc/xmmsc_sockets.h
/usr/include/xmms2/xmmsc/xmmsc_stdbool.h
/usr/include/xmms2/xmmsc/xmmsc_stdint.h
/usr/include/xmms2/xmmsc/xmmsc_stringport.h
/usr/include/xmms2/xmmsc/xmmsc_strlist.h
/usr/include/xmms2/xmmsc/xmmsc_unistd.h
/usr/include/xmms2/xmmsc/xmmsc_util.h
/usr/include/xmms2/xmmsc/xmmsc_visualization.h
/usr/include/xmms2/xmmsc/xmmsv.h
/usr/include/xmms2/xmmsc/xmmsv_bitbuffer.h
/usr/include/xmms2/xmmsc/xmmsv_build.h
/usr/include/xmms2/xmmsc/xmmsv_coll.h
/usr/include/xmms2/xmmsc/xmmsv_deprecated.h
/usr/include/xmms2/xmmsc/xmmsv_dict.h
/usr/include/xmms2/xmmsc/xmmsv_general.h
/usr/include/xmms2/xmmsc/xmmsv_list.h
/usr/include/xmms2/xmmsc/xmmsv_util.h