Bump AWS libraries to latest

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

vendor/github.com/aws/aws-sdk-go/private/protocol/json/jsonutil/build.go

@@ -82,13 +82,17 @@ func buildStruct(value reflect.Value, buf *bytes.Buffer, tag reflect.StructTag)
 		field, _ := value.Type().FieldByName(payload)
 		tag = field.Tag
 		value = elemOf(value.FieldByName(payload))
-
-		if !value.IsValid() {
+		if !value.IsValid() && tag.Get("type") != "structure" {
 			return nil
 		}
 	}
 
 	buf.WriteByte('{')
+	defer buf.WriteString("}")
+
+	if !value.IsValid() {
+		return nil
+	}
 
 	t := value.Type()
 	first := true
@@ -144,8 +148,6 @@ func buildStruct(value reflect.Value, buf *bytes.Buffer, tag reflect.StructTag)
 
 	}
 
-	buf.WriteString("}")
-
 	return nil
 }