clang-format: Make it more expensive to break template parameters.

In particular, make it more expensive than breaking after the return
type of a function definition/declaration.

Before:
  template <typename T>
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaa<
      T>::aaaaaaaaaaaaa(aaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaa);

After:
  template <typename T>
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
  aaaaaaaaaaaaaaaaaaaaaaa<T>::aaaaaaaaaaaaa(
      aaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaa);

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@260497 91177308-0d34-0410-b5e6-96231b3b80d8