Update for the changed obj_flag name in Varnish master.

src/vfp_brotli.c

@@ -349,7 +349,7 @@ vfp_br_init(struct vfp_ctx *ctx, struct vfp_entry *ent)
 	http_Unset(ctx->resp, H_Content_Encoding);
 	http_Unset(ctx->resp, H_Content_Length);
 	RFC2616_Weaken_Etag(ctx->resp);
-	ctx->obj_flags |= OF_CHGGZIP;
+	ctx->obj_flags |= OF_CHGCE;
 
 	if (settings->which == ENC) {
 		http_SetHeader(ctx->resp, "Content-Encoding: br");