clang-format: Fix switch/case interaction with macros.

Before:
  #define OPERATION_CASE(name) \
    case OP_name:              \
    return operations::Operation##name

  switch (OpCode) {
      CASE(Add);
      CASE(Subtract);
    default:
      return operations::Unknown;
  }

After:
  #define OPERATION_CASE(name) \
    case OP_name:              \
      return operations::Operation##name;

  switch (OpCode) {
    CASE(Add);
    CASE(Subtract);
    default:
      return operations::Unknown;
  }

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@187118 91177308-0d34-0410-b5e6-96231b3b80d8