defaults: add package to contain server defaults

To reduce the binary size of containerd, we no longer import the
`server` package for only a few defaults. This reduces the size of `ctr`
by 2MB. There are probably other gains elsewhere.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

cmd/containerd/config_linux.go

@@ -1,20 +1,21 @@
 package main
 
 import (
+	"github.com/containerd/containerd/defaults"
 	"github.com/containerd/containerd/server"
 )
 
 func defaultConfig() *server.Config {
 	return &server.Config{
-		Root:  server.DefaultRootDir,
-		State: server.DefaultStateDir,
+		Root:  defaults.DefaultRootDir,
+		State: defaults.DefaultStateDir,
 		GRPC: server.GRPCConfig{
-			Address: server.DefaultAddress,
+			Address: defaults.DefaultAddress,
 		},
 		Subreaper: true,
 		Debug: server.Debug{
 			Level:   "info",
-			Address: server.DefaultDebugAddress,
+			Address: defaults.DefaultDebugAddress,
 		},
 	}
 }