resolvectl: break nta/domain/dns listings with newlines

We would print the whole string as a single super-long line. Let's nicely
break the text into lines that fit on the screen.

$ COLUMNS=70 build/resolvectl --no-pager nta
Global: home local intranet 23.172.in-addr.arpa lan
        18.172.in-addr.arpa 16.172.in-addr.arpa 19.172.in-addr.arpa
        25.172.in-addr.arpa 21.172.in-addr.arpa d.f.ip6.arpa
        20.172.in-addr.arpa 30.172.in-addr.arpa 17.172.in-addr.arpa
        internal 168.192.in-addr.arpa 28.172.in-addr.arpa
        22.172.in-addr.arpa 24.172.in-addr.arpa 26.172.in-addr.arpa
        corp 10.in-addr.arpa private 29.172.in-addr.arpa test
        27.172.in-addr.arpa 31.172.in-addr.arpa
Link 2 (hub0):
Link 4 (enp0s31f6):
Link 5 (wlp4s0):
Link 7 (virbr0): adsfasdfasdfasd.com 21.172.in-addr.arpa lan j b
        a.com home d.f.ip6.arpa b.com local 16.172.in-addr.arpa
        19.172.in-addr.arpa 18.172.in-addr.arpa 25.172.in-addr.arpa
        20.172.in-addr.arpa k i h 23.172.in-addr.arpa
        168.192.in-addr.arpa d g intranet 17.172.in-addr.arpa c e.com
        30.172.in-addr.arpa a f d.com e internal
Link 8 (virbr0-nic):
Link 9 (vnet0):
Link 10 (vb-rawhide):
Link 15 (wwp0s20f0u2i12):

1 files changed, 2 insertions, 0 deletions

diff --git a/src/basic/macro.h b/src/basic/macro.h
index 41c2c3289e..954bb2de2a 100644
--- a/src/basic/macro.h
+++ b/src/basic/macro.h
@@ -634,4 +634,6 @@ static inline int __coverity_check_and_return__(int condition) {
                 _copy;                                                  \
         })
 
+#define SIZE_ADD(x, y) ((x) >= SIZE_MAX - (y) ? SIZE_MAX : (x) + (y))
+
 #include "log.h"