Refactor microbenchmarks

- Report CPU frequency only if it is successfully queried

PiperOrigin-RevId: 345756568
diff --git a/bench/channel-shuffle.cc b/bench/channel-shuffle.cc
index 97d5ab0..b45df59 100644
--- a/bench/channel-shuffle.cc
+++ b/bench/channel-shuffle.cc
@@ -73,7 +73,10 @@
     return;
   }
 
-  state.counters["Freq"] = benchmark::utils::GetCurrentCpuFrequency();
+  const uint64_t cpu_frequency = benchmark::utils::GetCurrentCpuFrequency();
+  if (cpu_frequency != 0) {
+    state.counters["cpufreq"] = cpu_frequency;
+  }
 
   const size_t elements_per_iteration = batch_size * groups * group_channels;
   state.counters["elements"] =
@@ -138,7 +141,10 @@
     return;
   }
 
-  state.counters["Freq"] = benchmark::utils::GetCurrentCpuFrequency();
+  const uint64_t cpu_frequency = benchmark::utils::GetCurrentCpuFrequency();
+  if (cpu_frequency != 0) {
+    state.counters["cpufreq"] = cpu_frequency;
+  }
 
   const size_t elements_per_iteration = batch_size * groups * group_channels;
   state.counters["elements"] =