kr_zonecut_add(): allow not checking for duplicates

Large block-lists in hints will end up in keeping a huge reverse map
for some IP address(es), and our simple duplicate-checking algorithm
can't handle that efficiently.  The duplicate checking in hints seems
better removed, so that add-del pairs work well in that case.
26 jobs for hints-huge in 54 minutes and 22 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build
passed #364042
amd64 linux docker
archive

00:00:53

passed #364067
docker linux amd64
build

00:00:49

passed #364044
amd64 linux docker
build-asan

00:00:55

passed #364045
docker
kres-gen

00:00:55

failed #364043
amd64 linux docker
build

00:00:54

 
  Test
passed #364046
docker delayed
build:darwin

00:00:25

passed #364047
amd64 linux docker
deckard

00:02:57

passed #364048
docker delayed
doc

00:01:26

passed #364049
dind
docker

00:01:59

passed #364050
docker delayed
lint:other

00:01:17

passed #364051
amd64 linux docker delayed
lint:pedantic

00:01:21

passed #364052
amd64 linux docker
lint:scan-build

00:02:49

passed #364053
amd64 linux docker
lint:tidy

00:03:39

passed #364054
amd64 linux docker
respdiff:basic

00:02:24

passed #364055
amd64 linux docker delayed
test:valgrind

00:02:26

 
  Extended
passed #364057
respdiff
fwd-tls6-kresd.udp6

00:29:22

passed #364058
respdiff
fwd-udp6-kresd.udp6

00:36:25

passed #364062
respdiff
fwd-udp6-unbound.tcp6

00:41:25

passed #364063
respdiff
fwd-udp6-unbound.tls6

00:40:55

passed #364061
respdiff
fwd-udp6-unbound.udp6

00:48:56

passed #364060
respdiff
iter.tls6

00:25:54

passed #364059
respdiff
iter.udp6

00:25:24

passed #364056
amd64 linux docker
pytests

00:04:10

passed #364064
respdiff
resperf:fwd-tls6.udp-asan

00:32:50

passed #364065
respdiff
resperf:fwd-udp6.udp-asan

00:34:20

passed #364066
respdiff
resperf:iter.udp-asan

00:20:49