clang-format: Improve function parameter packing.

Before:
  void SomeLoooooooooooongFunction(
      std::unique_ptr<aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa>
          aaaaaaaaaaaaaaaaaaaaaaaaaa, int bbbbbbbbbbbbb);

After:
  void SomeLoooooooooooongFunction(
      std::unique_ptr<aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa>
          aaaaaaaaaaaaaaaaaaaaaaaaaa,
      int bbbbbbbbbbbbb);

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@221989 91177308-0d34-0410-b5e6-96231b3b80d8