Fix building on glib < 2.58.0 as we have a minimum of 2.52.0
Review Request #573 — Created March 13, 2021 and submitted
Add compatibility for G_SOURCE_FUNC and g_time_zone_new_offset that were added in 2.58.0
g_time_zone_new_offset is from 2.58.0 which might be buggy, the version of it
from glib git has some fixes it but it is much more involved so using the older
version is a calculated risk.
Built on ubuntu:bionic.
