-Wextra-semi causes build failure on debian bullseye
From jenkins: https://jenkins.torproject.org/job/tor-ci-linux-master/ARCHITECTURE=amd64,SUITE=bullseye/4153/consoleFull
09:00:39 cc1: warning: command line option '-Wextra-semi' is valid for C++/ObjC++ but not for C
The logical solution here is to remove the flag.