Sync from Piper @476205078

PROTOBUF_SYNC_PIPER
diff --git a/conformance/conformance_test.h b/conformance/conformance_test.h
index 5adf3f9..f03b6d7 100644
--- a/conformance/conformance_test.h
+++ b/conformance/conformance_test.h
@@ -276,7 +276,7 @@
   void ReportFailure(const std::string& test_name, ConformanceLevel level,
                      const conformance::ConformanceRequest& request,
                      const conformance::ConformanceResponse& response,
-                     const char* fmt, ...);
+                     absl::string_view message);
   void ReportSkip(const std::string& test_name,
                   const conformance::ConformanceRequest& request,
                   const conformance::ConformanceResponse& response);