message: Fix integer casting issues in Mac OSS build
  Summary:
  We were getting the following error:
  ```
  error: return type 'long long' must match previous return
  type 'long' when lambda expression has unspecified explicit return type
  ```
  Addresses
diff: @@ -19,10 +19,10 @@ void SimplifyCFGPass::run_pass(DexStoresVector& stores,
  auto total_insns_removed =
  walk::parallel::reduce_methods<std::nullptr_t, int64_t, Scope>(
  scope,
  - [](std::nullptr_t, DexMethod* m) {
  + [](std::nullptr_t, DexMethod* m) -> int64_t {
  auto code = m->get_code();
  if (code == nullptr) {
  - return 0l;
  + return 0;
  }
  int64_t before_insns = code->count_opcodes();
  