FS#3998 - netifd: domain search list is written to resolv.conf incorrectly

[openwrt-bot]

lutchann:

write_resolv_conf_entries() writes the DNS search domains to resolv.conf.auto one per line, whereas the musl resolver expects all domains to be listed on one line, separated by spaces.

I.e., netifd currently writes this:

# Interface lan
nameserver 192.168.100.100
search domain1.com
search domain2.com

But musl wants this:

# Interface lan
nameserver 192.168.100.100
search domain1.com domain2.com

While other resolvers are happy to append multiple "search" lines together to form the domain search list, musl overwrites its domain search list every time a new "search" line is encountered. The result is that only the lowest priority search domain specified by the network administrator is searched.