message: Fix warning caused by new clang::BuiltinType::Float16 added in r312794
diff: @@ -5009,6 +5009,7 @@ lldb::Encoding ClangASTContext::GetEncoding(lldb::opaque_compiler_type_t type,
  case clang::BuiltinType::Half:
  case clang::BuiltinType::Float:
  + case clang::BuiltinType::Float16:
  case clang::BuiltinType::Float128:
  case clang::BuiltinType::Double:
  case clang::BuiltinType::LongDouble:
  