Make connection errors display backwards compatible

Only show connection errors in the per-second progress output
when there are actual errors. This ensures the output format
remains backwards compatible with existing scripts and tools
that parse memtier output.

Before:
  [RUN #1 50%, 10 secs] 4 threads 20 conns 0 conn errors: 1000 ops...

After (no errors):
  [RUN #1 50%, 10 secs] 4 threads 20 conns: 1000 ops...

After (with errors):
  [RUN #1 50%, 10 secs] 4 threads 20 conns 5 conn errors: 1000 ops...

Also added ThreadSanitizer suppressions for connection error
tracking functions to match existing suppressions for other
stats counters.

Author: fcostaoliveira

memtier_benchmark.cpp

@@ -1520,8 +1520,14 @@ run_stats run_benchmark(int run_id, benchmark_config* cfg, object_generator* obj
         else
             progress = 100.0 * (duration / 1000000.0)/cfg->test_time;
 
-        fprintf(stderr, "[RUN #%u %.0f%%, %3u secs] %2u threads %2u conns %lu conn errors: %11lu ops, %7lu (avg: %7lu) ops/sec, %s/sec (avg: %s/sec), %5.2f (avg: %5.2f) msec latency\r",
-            run_id, progress, (unsigned int) (duration / 1000000), active_threads, cfg->clients, total_connection_errors, total_ops, cur_ops_sec, ops_sec, cur_bytes_str, bytes_str, cur_latency, avg_latency);
+        // Only show connection errors if there are any (backwards compatible output)
+        if (total_connection_errors > 0) {
+            fprintf(stderr, "[RUN #%u %.0f%%, %3u secs] %2u threads %2u conns %lu conn errors: %11lu ops, %7lu (avg: %7lu) ops/sec, %s/sec (avg: %s/sec), %5.2f (avg: %5.2f) msec latency\r",
+                run_id, progress, (unsigned int) (duration / 1000000), active_threads, cfg->clients, total_connection_errors, total_ops, cur_ops_sec, ops_sec, cur_bytes_str, bytes_str, cur_latency, avg_latency);
+        } else {
+            fprintf(stderr, "[RUN #%u %.0f%%, %3u secs] %2u threads %2u conns: %11lu ops, %7lu (avg: %7lu) ops/sec, %s/sec (avg: %s/sec), %5.2f (avg: %5.2f) msec latency\r",
+                run_id, progress, (unsigned int) (duration / 1000000), active_threads, cfg->clients, total_ops, cur_ops_sec, ops_sec, cur_bytes_str, bytes_str, cur_latency, avg_latency);
+        }
     } while (active_threads > 0);
 
     fprintf(stderr, "\n\n");