ggml : do not print perf ops that have not been used at all

ggml.c

@@ -11237,7 +11237,7 @@ void ggml_graph_print(const struct ggml_cgraph * cgraph) {
     for (int i = 0; i < cgraph->n_nodes; i++) {
         struct ggml_tensor * node = cgraph->nodes[i];
 
-        perf_total_per_op_us[node->op] += node->perf_time_us;
+        perf_total_per_op_us[node->op] += MAX(1, node->perf_time_us);
 
         GGML_PRINT(" - %3d: [ %5" PRId64 ", %5" PRId64 ", %5" PRId64 "] %16s %s (%3d) cpu = %7.3f / %7.3f ms, wall = %7.3f / %7.3f ms\n",
                 i,
@@ -11260,6 +11260,10 @@ void ggml_graph_print(const struct ggml_cgraph * cgraph) {
     }
 
     for (int i = 0; i < GGML_OP_COUNT; i++) {
+        if (perf_total_per_op_us[i] == 0) {
+            continue;
+        }
+
         GGML_PRINT("perf_total_per_op_us[%16s] = %7.3f ms\n", GGML_OP_LABEL[i], (double) perf_total_per_op_us[i] / 1000.0);
     }