- drop linux-4.15.patch: No longer needed as it was a backport from
upstream
- Cleanup configure options after consultation with upstream:
- --enable-regex-timers is for debugging purposes
- --enable-snmp-checker and --enable-snmp-vrrp are enabled by
--enable-snmp
- --enable-snmp-rfcv2 and --enable-snmp-rfcv3 anre enabled by
--enable-snmp-rfc
- --enable-stacktrace is definitely a debugging option
- on systems where we have nftables support we will only ship with
nftables support (>= 15.0) and use iptables support only on older
distributions.