all: Update protobuf package 1.0.0 -> 1.2.0 (#5452)

Also adds a few file global options to keep the generated code similar
to what we already had.

vendor/github.com/gogo/protobuf/proto/lib_gogo.go

@@ -33,6 +33,14 @@ import (
 	"strconv"
 )
 
+type Sizer interface {
+	Size() int
+}
+
+type ProtoSizer interface {
+	ProtoSize() int
+}
+
 func MarshalJSONEnum(m map[int32]string, value int32) ([]byte, error) {
 	s, ok := m[value]
 	if !ok {