disable trace-cmp on llvm_libcxx to make it faster, see https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5377

projects/llvm_libcxx/build.sh

@@ -18,6 +18,8 @@
 if [[ $SANITIZER = *undefined* ]]; then
   CXXFLAGS="$CXXFLAGS -fsanitize=unsigned-integer-overflow -fsanitize-trap=unsigned-integer-overflow"
 fi
+# trace-cmp makes this target too slow.
+CXXFLAGS="$CXXFLAGS -fno-sanitize-coverage=trace-cmp"
 
 for f in $(grep -v "#" libcxx/fuzzing/RoutineNames.txt); do
   cat > ${f}_fuzzer.cc <<EOF