message: Add metric to count number of performed passes
diff: constexpr const char* METRIC_GETTERS_REMOVED = "getter_methods_removed_count";
  constexpr const char* METRIC_WRAPPERS_REMOVED = "wrapper_methods_removed_count";
  constexpr const char* METRIC_CTORS_REMOVED = "constructors_removed_count";
  +constexpr const char* METRIC_PASSES = "passes_count";
  namespace {
  struct SynthMetrics {
  @@ -867,6 +868,7 @@ void SynthPass::run_pass(DexStoresVector& stores,
  mgr.incr_metric(METRIC_GETTERS_REMOVED, metrics.getters_removed_count);
  mgr.incr_metric(METRIC_WRAPPERS_REMOVED, metrics.wrappers_removed_count);
  mgr.incr_metric(METRIC_CTORS_REMOVED, metrics.ctors_removed_count);
  + mgr.incr_metric(METRIC_PASSES, passes);
  }
  static SynthPass s_pass;
  