runners: Don't include case-less suites in -Y/--summary

Note --list-suite-paths was already skipping case-less suites! I think
only -Y/--summary was an outlier.

This is consistent with test.py's matching of suite ids when no cases
are found (test_runner itself doesn't really care, it just reports no
matching cases). Though we do still compile case-less suites and include
them in the test_suites array, which may be confusing in the future.

runners/bench_runner.c

@@ -863,6 +863,8 @@ static void summary(void) {
         for (size_t i = 0; i < bench_suite_count; i++) {
             bench_define_suite(&bench_ids[t], bench_suites[i]);
 
+            size_t cases_ = 0;
+
             for (size_t j = 0; j < bench_suites[i]->case_count; j++) {
                 // does neither suite nor case name match?
                 if (bench_ids[t].name && !(
@@ -874,6 +876,7 @@ static void summary(void) {
                 }
 
                 cases += 1;
+                cases_ += 1;
                 case_forperm(
                         &bench_ids[t],
                         bench_suites[i],
@@ -882,6 +885,11 @@ static void summary(void) {
                         &perms);
             }
 
+            // no benches found?
+            if (!cases_) {
+                continue;
+            }
+
             suites += 1;
             flags |= bench_suites[i]->flags;
         }