clang-format: Don't merge const and &, e.g. in function ref qualifiers.

Before (when aligning & to the right):
  SomeType MemberFunction(const Deleted &) const&;

After:
  SomeType MemberFunction(const Deleted &) const &;

This also applies to variable declarations, e.g.:
  int const * a;

However, this form is very uncommon (most people would write
"const int* a" instead) and contracting to "const*" might actually send
the wrong signal of what the const binds to.

llvm-svn: 272537