clang-format: Fix return type line break decision.

This accidentally introduced by r186077, as function names were not
correctly recognized in templated declarations.

Before:
  template <class TemplateIt>
  SomeReturnType
  SomeFunction(TemplateIt begin, TemplateIt end, TemplateIt* stop) {}

After:
  template <class TemplateIt>
  SomeReturnType SomeFunction(TemplateIt begin, TemplateIt end,
                              TemplateIt* stop) {}