Link error on macOS

[277/284] Linking build/main/attic/sht
Undefined symbols for architecture x86_64:
  "_debug", referenced from:
      _change_logfile in libntp.a(msyslog.c.1.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

git bisect shows the error first occurs with 9eae92b6