/usr/include/ is in libspice-client-glib-2.0-dev 0.33-3.3+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/spice-client-glib-2.0/
/usr/include/spice-client-glib-2.0/channel-cursor.h
/usr/include/spice-client-glib-2.0/channel-display.h
/usr/include/spice-client-glib-2.0/channel-inputs.h
/usr/include/spice-client-glib-2.0/channel-main.h
/usr/include/spice-client-glib-2.0/channel-playback.h
/usr/include/spice-client-glib-2.0/channel-port.h
/usr/include/spice-client-glib-2.0/channel-record.h
/usr/include/spice-client-glib-2.0/channel-smartcard.h
/usr/include/spice-client-glib-2.0/channel-usbredir.h
/usr/include/spice-client-glib-2.0/channel-webdav.h
/usr/include/spice-client-glib-2.0/smartcard-manager.h
/usr/include/spice-client-glib-2.0/spice-audio.h
/usr/include/spice-client-glib-2.0/spice-channel-enums.h
/usr/include/spice-client-glib-2.0/spice-channel.h
/usr/include/spice-client-glib-2.0/spice-client.h
/usr/include/spice-client-glib-2.0/spice-file-transfer-task.h
/usr/include/spice-client-glib-2.0/spice-glib-enums.h
/usr/include/spice-client-glib-2.0/spice-option.h
/usr/include/spice-client-glib-2.0/spice-session.h
/usr/include/spice-client-glib-2.0/spice-types.h
/usr/include/spice-client-glib-2.0/spice-uri.h
/usr/include/spice-client-glib-2.0/spice-util.h
/usr/include/spice-client-glib-2.0/spice-version.h
/usr/include/spice-client-glib-2.0/usb-device-manager.h
/usr/include/spice-controller/
/usr/include/spice-controller/spice-controller.h