Merge pull request #15136 from yuwata/network-dhcp4-use-gateway

network: add a flag to ignore gateway provided by DHCP server

diff --cc man/systemd.network.xml
Simple merge

diff --cc src/network/networkd-dhcp4.c
Simple merge

diff --cc src/network/networkd-network-gperf.gperf
Simple merge

diff --cc src/network/networkd-network.h
Simple merge

diff --cc test/fuzz/fuzz-network-parser/directives.network
Simple merge