Bump gc threshold to 40%

Doing tests, this is a better balance for the threshold in reguards to
memory and cpu usage.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/containerd-shim/main_unix.go

@@ -60,7 +60,7 @@ func init() {
 }
 
 func main() {
-	debug.SetGCPercent(10)
+	debug.SetGCPercent(40)
 	go func() {
 		for range time.Tick(30 * time.Second) {
 			debug.FreeOSMemory()

linux/proc/types.go

@@ -4,6 +4,7 @@ import (
 	google_protobuf "github.com/gogo/protobuf/types"
 )
 
+// Mount holds filesystem mount configuration
 type Mount struct {
 	Type    string
 	Source  string