dnsmasq: Add broken realtime clock build switch in full variant

dnsmasq: Add broken realtime clock build switch in full variant

By default dnsmasq uses the time function; which returns the time since
Epoch; to retrieve the current time. On boards which have no realtime
clock this can lead to side effects when the time is synced via ntp
as the "time wrap" forces dhcp leases to be considered as expired.
By enabling the broken realtime clock build switch dnsmasq uses the
times utility which returns the number of clock tick.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>
[Jo-Philipp Wich: change symbol name, add sym to PKG_CONFIG_DEPENDS]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>