clang-format: Get slightly better at understanding */&.

Before:
  void f() { MACRO(A * const a); }

After:
  void f() { MACRO(A *const a); }

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@297268 91177308-0d34-0410-b5e6-96231b3b80d8