encoding/protobuf: don't mark a single enum value as default

Issue #5

Change-Id: Icb6e8b5c6c490ea7123e554a9fb86a2b8d8ba624
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/2373
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
diff --git a/encoding/protobuf/testdata/client_config.proto.out.cue b/encoding/protobuf/testdata/client_config.proto.out.cue
index efa1f40..66ec87a 100644
--- a/encoding/protobuf/testdata/client_config.proto.out.cue
+++ b/encoding/protobuf/testdata/client_config.proto.out.cue
@@ -42,19 +42,13 @@
 	maxRetryWait?: time.Duration @protobuf(4,type=google.protobuf.Duration,name=max_retry_wait)
 }
 
-//  Describes the policy.
+//  Example of single-value enum.
 NetworkFailPolicy_FailPolicy:
 	//  If network connection fails, request is allowed and delivered to the
 	//  service.
-	*"FAIL_OPEN" |
+	"FAIL_OPEN"
 
-	//  If network connection fails, request is rejected.
-	"FAIL_CLOSE"
-
-NetworkFailPolicy_FailPolicy_value: {
-	FAIL_OPEN:  0
-	FAIL_CLOSE: 1
-}
+NetworkFailPolicy_FailPolicy_value FAIL_OPEN: 0
 
 //  Defines the per-service client configuration.
 ServiceConfig: {