p2.7: prometheus /metrics

Default GET /metrics is Prometheus text; JSON stays at /metrics.json
and ?format=json. :8443 needs the metrics caller bearer; loopback
stays open. Restricted callers have no per-caller series and no
tavily:restricted gauge.

vendor/google.golang.org/protobuf/internal/descopts/options.go

@@ -0,0 +1,29 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package descopts contains the nil pointers to concrete descriptor options.
+//
+// This package exists as a form of reverse dependency injection so that certain
+// packages (e.g., internal/filedesc and internal/filetype can avoid a direct
+// dependency on the descriptor proto package).
+package descopts
+
+import "google.golang.org/protobuf/reflect/protoreflect"
+
+// These variables are set by the init function in descriptor.pb.go via logic
+// in internal/filetype. In other words, so long as the descriptor proto package
+// is linked in, these variables will be populated.
+//
+// Each variable is populated with a nil pointer to the options struct.
+var (
+	File           protoreflect.ProtoMessage
+	Enum           protoreflect.ProtoMessage
+	EnumValue      protoreflect.ProtoMessage
+	Message        protoreflect.ProtoMessage
+	Field          protoreflect.ProtoMessage
+	Oneof          protoreflect.ProtoMessage
+	ExtensionRange protoreflect.ProtoMessage
+	Service        protoreflect.ProtoMessage
+	Method         protoreflect.ProtoMessage
+)