dnsmasq: follow upstream dnsmasq pre-v2.81 v2

dnsmasq: follow upstream dnsmasq pre-v2.81 v2

Backport upstream commits.  Most interesting 122392e which changes how
SERVFAIL is handled especially in event of genuine server down/failure
scenarios with multiple servers.  a799ca0 also interesting in that
answered received via TCP are now cached, DNSSEC typically using TCP
meant until now answers weren't cached, hence reducing performance.

59e4703 Free config file values on parsing errors.
48d12f1 Remove the NO_FORK compile-time option, and support for uclinux.
122392e Revert 68f6312d4bae30b78daafcd6f51dc441b8685b1e
3a5a84c Fix Makefile lines generating UBUS linker config.
24b8760 Do not rely on dead code elimination, use array instead. Make options bits derived from size and count. Use size of option bits and last supported bit in computation. No new change would be required when new options are added. Just change OPT_LAST constant.
6f7812d Fix spurious AD flags in some DNS replies from local config.
cbb5b17 Fix logging in cf5984367bc6a949e3803a576512c5a7bc48ebab
cf59843 Don't forward *.bind/*.server queries upstream
ee87504 Remove ability to compile without IPv6 support.
a220545 Ensure that AD bit is reset on answers from --address=/<domain>/<address>.
a799ca0 Impove cache behaviour for TCP connections.

Along with an additional patch to fix compilation without DHCPv6, sent
upstream.

I've been running this for aaaages without obvious issue hence brave
step of opening to wider openwrt community.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
(backported from 8c0f6a010a5b7011acbbf2ac5b345d9cf1c14b1f)