clang-format: Improve indentation when deriving from templated classes.

Before:
  struct aaaaaaaaaaaaa : public aaaaaaaaaaaaaaaaaaa< //
      aaaaaaaaaaaaaaaa> {};
  struct aaaaaaaaaaaaaaaaaaaa : public aaaaaaaaaaaaaaaaaaa<
      aaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaa> {};

After:
  struct aaaaaaaaaaaaa : public aaaaaaaaaaaaaaaaaaa< //
                             aaaaaaaaaaaaaaaa> {};
  struct aaaaaaaaaaaaaaaaaaaa
      : public aaaaaaaaaaaaaaaaaaa<aaaaaaaaaaaaaaaaaaaaa,
                                   aaaaaaaaaaaaaaaaaaaaaa> {};