sanitizer_common: Suppress another thread safety warning

Another follow-up to 0da172b1

compiler-rt/lib/scudo/scudo_tsd_shared.cpp:103:1: error: mutex 'CandidateTSD->Mutex' is not held on every path through here [-Werror,-Wthread-safety-analysis]
}
^
compiler-rt/lib/scudo/scudo_tsd_shared.cpp:95:21: note: mutex acquired here
      CandidateTSD->lock();
                    ^
compiler-rt/lib/scudo/scudo_tsd_shared.cpp:103:1: error: mutex 'TSD->Mutex' is not held on every path through here [-Werror,-Wthread-safety-analysis]
}
^
compiler-rt/lib/scudo/scudo_tsd_shared.cpp:101:8: note: mutex acquired here
  TSD->lock();
       ^
compiler-rt/lib/scudo/scudo_tsd_shared.cpp:103:1: error: mutex 'TSDs[Index].Mutex' is not held on every path through here [-Werror,-Wthread-safety-analysis]
}
^
compiler-rt/lib/scudo/scudo_tsd_shared.cpp:80:23: note: mutex acquired here
      if (TSDs[Index].tryLock()) {
                      ^