[clang-format] let PointerAlignment dictate spacing of function ref qualifiers

Summary: The original changes for ref qualifiers in rL272537 and rL272548 allowed function const+ref qualifier spacing to diverge from the spacing used for variables. It seems more consistent for `T const& x;` to match `void foo() const&;`.

Reviewers: djasper

Reviewed By: djasper

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D34324

llvm-svn: 310544