clang-format: Fix enum formatting with specific comment.

Before:
  enum Fruit {  //
    APPLE,
    PEAR };

After:
  enum Fruit {  //
    APPLE,
    PEAR
  };

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@210522 91177308-0d34-0410-b5e6-96231b3b80d8