third_party/protobuf: Update to HEAD (83d681ee2c)

third_party/protobuf/objectivec/GPBRootObject.h

Index: third_party/protobuf/objectivec/GPBRootObject.h
diff --git a/third_party/protobuf/objectivec/GPBRootObject.h b/third_party/protobuf/objectivec/GPBRootObject.h
index c05b5c620f37a45fb775c3f187fc9e525d9a2a45..d2e2aebfcc57ab092344f550fd8dcb535a4545e2 100644
--- a/third_party/protobuf/objectivec/GPBRootObject.h
+++ b/third_party/protobuf/objectivec/GPBRootObject.h
@@ -34,12 +34,17 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-/// Every generated proto file defines a local "Root" class that exposes a
-/// @c GPBExtensionRegistry for all the extensions defined by that file and
-/// the files it depends on.
+/**
+ * Every generated proto file defines a local "Root" class that exposes a
+ * GPBExtensionRegistry for all the extensions defined by that file and
+ * the files it depends on.
+ **/
 @interface GPBRootObject : NSObject
 
-/// An extension registry for the given file and all the files it depends on.
+/**
+ * @return An extension registry for the given file and all the files it depends
+ * on.
+ **/
 + (GPBExtensionRegistry *)extensionRegistry;
 
 @end