Add -Wswitch-enum

Change code so when switching on an enumeration, have case's for all
enumeration values.

Reviewed-by: Andy Polyakov <appro@openssl.org>
diff --git a/test/ct_test.c b/test/ct_test.c
index 6c96268..705fbfb 100644
--- a/test/ct_test.c
+++ b/test/ct_test.c
@@ -244,7 +244,10 @@
         case SCT_VALIDATION_STATUS_INVALID:
             ++invalid_sct_count;
             break;
-        default:
+        case SCT_VALIDATION_STATUS_NOT_SET:
+        case SCT_VALIDATION_STATUS_UNKNOWN_LOG:
+        case SCT_VALIDATION_STATUS_UNVERIFIED:
+        case SCT_VALIDATION_STATUS_UNKNOWN_VERSION:
             /* Ignore other validation statuses. */
             break;
         }