vendor: update all dependencies

* Update all dependencies
  * Remove all `[[constraint]]` from Gopkg.toml
  * Add in the minimum number of `[[override]]` to build
  * Remove go get of github.com/inconshreveable/mousetrap as it is vendored
  * Update docs with new policy on constraints

vendor/github.com/golang/protobuf/proto/message_set.go

@@ -42,6 +42,7 @@ import (
 	"fmt"
 	"reflect"
 	"sort"
+	"sync"
 )
 
 // errNoMessageTypeID occurs when a protocol buffer does not have a message type ID.
@@ -94,10 +95,7 @@ func (ms *messageSet) find(pb Message) *_MessageSet_Item {
 }
 
 func (ms *messageSet) Has(pb Message) bool {
-	if ms.find(pb) != nil {
-		return true
-	}
-	return false
+	return ms.find(pb) != nil
 }
 
 func (ms *messageSet) Unmarshal(pb Message) error {
@@ -150,46 +148,42 @@ func skipVarint(buf []byte) []byte {
 // MarshalMessageSet encodes the extension map represented by m in the message set wire format.
 // It is called by generated Marshal methods on protocol buffer messages with the message_set_wire_format option.
 func MarshalMessageSet(exts interface{}) ([]byte, error) {
-	var m map[int32]Extension
+	return marshalMessageSet(exts, false)
+}
+
+// marshaMessageSet implements above function, with the opt to turn on / off deterministic during Marshal.
+func marshalMessageSet(exts interface{}, deterministic bool) ([]byte, error) {
 	switch exts := exts.(type) {
 	case *XXX_InternalExtensions:
-		if err := encodeExtensions(exts); err != nil {
-			return nil, err
-		}
-		m, _ = exts.extensionsRead()
+		var u marshalInfo
+		siz := u.sizeMessageSet(exts)
+		b := make([]byte, 0, siz)
+		return u.appendMessageSet(b, exts, deterministic)
+
 	case map[int32]Extension:
-		if err := encodeExtensionsMap(exts); err != nil {
-			return nil, err
+		// This is an old-style extension map.
+		// Wrap it in a new-style XXX_InternalExtensions.
+		ie := XXX_InternalExtensions{
+			p: &struct {
+				mu           sync.Mutex
+				extensionMap map[int32]Extension
+			}{
+				extensionMap: exts,
+			},
 		}
-		m = exts
+
+		var u marshalInfo
+		siz := u.sizeMessageSet(&ie)
+		b := make([]byte, 0, siz)
+		return u.appendMessageSet(b, &ie, deterministic)
+
 	default:
 		return nil, errors.New("proto: not an extension map")
 	}
-
-	// Sort extension IDs to provide a deterministic encoding.
-	// See also enc_map in encode.go.
-	ids := make([]int, 0, len(m))
-	for id := range m {
-		ids = append(ids, int(id))
-	}
-	sort.Ints(ids)
-
-	ms := &messageSet{Item: make([]*_MessageSet_Item, 0, len(m))}
-	for _, id := range ids {
-		e := m[int32(id)]
-		// Remove the wire type and field number varint, as well as the length varint.
-		msg := skipVarint(skipVarint(e.enc))
-
-		ms.Item = append(ms.Item, &_MessageSet_Item{
-			TypeId:  Int32(int32(id)),
-			Message: msg,
-		})
-	}
-	return Marshal(ms)
 }
 
 // UnmarshalMessageSet decodes the extension map encoded in buf in the message set wire format.
-// It is called by generated Unmarshal methods on protocol buffer messages with the message_set_wire_format option.
+// It is called by Unmarshal methods on protocol buffer messages with the message_set_wire_format option.
 func UnmarshalMessageSet(buf []byte, exts interface{}) error {
 	var m map[int32]Extension
 	switch exts := exts.(type) {
@@ -235,7 +229,15 @@ func MarshalMessageSetJSON(exts interface{}) ([]byte, error) {
 	var m map[int32]Extension
 	switch exts := exts.(type) {
 	case *XXX_InternalExtensions:
-		m, _ = exts.extensionsRead()
+		var mu sync.Locker
+		m, mu = exts.extensionsRead()
+		if m != nil {
+			// Keep the extensions map locked until we're done marshaling to prevent
+			// races between marshaling and unmarshaling the lazily-{en,de}coded
+			// values.
+			mu.Lock()
+			defer mu.Unlock()
+		}
 	case map[int32]Extension:
 		m = exts
 	default:
@@ -253,15 +255,16 @@ func MarshalMessageSetJSON(exts interface{}) ([]byte, error) {
 
 	for i, id := range ids {
 		ext := m[id]
-		if i > 0 {
-			b.WriteByte(',')
-		}
-
 		msd, ok := messageSetMap[id]
 		if !ok {
 			// Unknown type; we can't render it, so skip it.
 			continue
 		}
+
+		if i > 0 && b.Len() > 1 {
+			b.WriteByte(',')
+		}
+
 		fmt.Fprintf(&b, `"[%s]":`, msd.name)
 
 		x := ext.value