/usr/include/libical-glib/ is in libical-dev 3.0.1-5.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libical-glib/i-cal-array.h
/usr/include/libical-glib/i-cal-attach.h
/usr/include/libical-glib/i-cal-comp-iter.h
/usr/include/libical-glib/i-cal-component.h
/usr/include/libical-glib/i-cal-datetimeperiod-type.h
/usr/include/libical-glib/i-cal-derived-parameter.h
/usr/include/libical-glib/i-cal-derived-property.h
/usr/include/libical-glib/i-cal-derived-value.h
/usr/include/libical-glib/i-cal-duration-type.h
/usr/include/libical-glib/i-cal-enums.h
/usr/include/libical-glib/i-cal-error.h
/usr/include/libical-glib/i-cal-forward-declarations.h
/usr/include/libical-glib/i-cal-geo-type.h
/usr/include/libical-glib/i-cal-langbind.h
/usr/include/libical-glib/i-cal-memory.h
/usr/include/libical-glib/i-cal-mime.h
/usr/include/libical-glib/i-cal-object.h
/usr/include/libical-glib/i-cal-parameter.h
/usr/include/libical-glib/i-cal-parser.h
/usr/include/libical-glib/i-cal-period-type.h
/usr/include/libical-glib/i-cal-property.h
/usr/include/libical-glib/i-cal-recur-iterator.h
/usr/include/libical-glib/i-cal-recur.h
/usr/include/libical-glib/i-cal-recurrence-type.h
/usr/include/libical-glib/i-cal-reqstat-type.h
/usr/include/libical-glib/i-cal-restriction.h
/usr/include/libical-glib/i-cal-time-span.h
/usr/include/libical-glib/i-cal-time.h
/usr/include/libical-glib/i-cal-timetype.h
/usr/include/libical-glib/i-cal-timezone-phase.h
/usr/include/libical-glib/i-cal-timezone.h
/usr/include/libical-glib/i-cal-timezonetype.h
/usr/include/libical-glib/i-cal-trigger-type.h
/usr/include/libical-glib/i-cal-unknowntokenhandling.h
/usr/include/libical-glib/i-cal-value.h
/usr/include/libical-glib/libical-glib.h