== PoC build (guest, unprivileged maxx, cc 8.3 [DragonFly]) ==
$ cc -O2 -o /tmp/df3456/ab /tmp/df3456/anchor_bypass.c
/tmp/df3456/anchor_bypass.c: In function 'flood_mode':
/tmp/df3456/anchor_bypass.c:127:3: warning: implicit declaration of function 'wait'; did you mean 'write'? [-Wimplicit-function-declaration]
   wait(NULL);
   ^~~
   write
BUILD_OK

$ cc -O2 -o /tmp/df3456/dns /tmp/df3456/dns_flood.c
BUILD_OK (no warnings)