daemon: read-copy-update the daemon config

Ensure data-race-free access to the daemon configuration without
locking by mutating a deep copy of the config and atomically storing
a pointer to the copy into the daemon-wide configStore value. Any
operations which need to read from the daemon config must capture the
configStore value only once and pass it around to guarantee a consistent
view of the config.

Signed-off-by: Cory Snider <csnider@mirantis.com>

daemon/inspect_linux.go

@@ -29,7 +29,7 @@ func (daemon *Daemon) containerInspectPre120(ctx context.Context, name string) (
 	ctr.Lock()
 	defer ctr.Unlock()
 
-	base, err := daemon.getInspectData(ctr)
+	base, err := daemon.getInspectData(daemon.config(), ctr)
 	if err != nil {
 		return nil, err
 	}