clang-format: Prefer formatting local lambdas like functions.

Before:
  auto my_lambda =
      [](const string &some_parameter) { return some_parameter.size(); };

After:
  auto my_lambda = [](const string &some_parameter) {
    return some_parameter.size();
  };

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@237235 91177308-0d34-0410-b5e6-96231b3b80d8