clang-format: Spacing inside enum braces.

Before (in Google style):
  enum ShortEnum {A, B, C};

After:
  enum ShortEnum { A, B, C };

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@198559 91177308-0d34-0410-b5e6-96231b3b80d8