Fixes the compile to work with LLVM15 (#9410)

Author: zwoop

iocore/eventsystem/UnixEventProcessor.cc

@@ -522,15 +522,15 @@ EventProcessor::start(int n_event_threads, size_t stacksize)
 
   // Event loop timings.
   for (Graph::raw_type id = 0; id < Graph::N_BUCKETS; ++id) {
-    snprintf(name, sizeof(name), "%s%" PRIu64 "ms", EThread::Metrics::LOOP_HISTOGRAM_STAT_STEM.data(),
-             EThread::Metrics::LOOP_HISTOGRAM_BUCKET_SIZE.count() * Graph::lower_bound(id));
+    snprintf(name, sizeof(name), "%s%zums", EThread::Metrics::LOOP_HISTOGRAM_STAT_STEM.data(),
+             static_cast<size_t>(EThread::Metrics::LOOP_HISTOGRAM_BUCKET_SIZE.count() * Graph::lower_bound(id)));
     RecRegisterRawStat(rsb, RECT_PROCESS, name, RECD_INT, RECP_NON_PERSISTENT, stat_idx++, NULL);
   }
 
   // plugin API timings
   for (Graph::raw_type id = 0; id < Graph::N_BUCKETS; ++id) {
-    snprintf(name, sizeof(name), "%s%" PRIu64 "ms", EThread::Metrics::API_HISTOGRAM_STAT_STEM.data(),
-             EThread::Metrics::API_HISTOGRAM_BUCKET_SIZE.count() * Graph::lower_bound(id));
+    snprintf(name, sizeof(name), "%s%zums", EThread::Metrics::API_HISTOGRAM_STAT_STEM.data(),
+             static_cast<size_t>(EThread::Metrics::API_HISTOGRAM_BUCKET_SIZE.count() * Graph::lower_bound(id)));
     RecRegisterRawStat(rsb, RECT_PROCESS, name, RECD_INT, RECP_NON_PERSISTENT, stat_idx++, NULL);
   }