clang-format: Don't remove newline if macro ends in access specifier.

I.e.:

  #define A public:

  // The new line before this line would be removed.
  int a;

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@231636 91177308-0d34-0410-b5e6-96231b3b80d8