Import upstream patch:
icaltzutil_fetch_timezone now creates VTIMEZONE components using RRULEs rather than expanding out every year (if USE_INTEROPERATIVE_VTIMEZONES was off) or using a single time zone back to 1970 (if it was one). This creates more accurate time zones that are compatible with dates whose time zones have since transitioned to a different offset (such as a date in America/New_York in 1980). Removed icaltzutil_set_exact_vtimezones_support and icaltzutil_get_exact_vtimezones_support. Removed USE_INTEROPERABLE_VTIMEZONES.
Add missing USE_GNOME=introspection:build
Fix segmentation fault with evolution-calendar-factory
Pet portlint, USE_* comes before USES
Submitted by: cpm
Obtained from: github libical/libical (partially)