Remove global cfg variable (fixes #2294)

Not necessarily the easiest way to fix just this bug, but the root cause
was using the (at that point uninitialized) cfg variable, so it seemed
sensible to just get rid of it to avoid that kind of crap.

cmd/syncthing/summarysvc.go

@@ -9,6 +9,7 @@ package main
 import (
 	"time"
 
+	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/model"
 	"github.com/syncthing/syncthing/lib/sync"
@@ -20,6 +21,7 @@ import (
 type folderSummarySvc struct {
 	*suture.Supervisor
 
+	cfg       *config.Wrapper
 	model     *model.Model
 	stop      chan struct{}
 	immediate chan string
@@ -33,9 +35,10 @@ type folderSummarySvc struct {
 	lastEventReqMut sync.Mutex
 }
 
-func newFolderSummarySvc(m *model.Model) *folderSummarySvc {
+func newFolderSummarySvc(cfg *config.Wrapper, m *model.Model) *folderSummarySvc {
 	svc := &folderSummarySvc{
 		Supervisor:      suture.NewSimple("folderSummarySvc"),
+		cfg:             cfg,
 		model:           m,
 		stop:            make(chan struct{}),
 		immediate:       make(chan string),
@@ -162,13 +165,13 @@ func (c *folderSummarySvc) foldersToHandle() []string {
 func (c *folderSummarySvc) sendSummary(folder string) {
 	// The folder summary contains how many bytes, files etc
 	// are in the folder and how in sync we are.
-	data := folderSummary(c.model, folder)
+	data := folderSummary(c.cfg, c.model, folder)
 	events.Default.Log(events.FolderSummary, map[string]interface{}{
 		"folder":  folder,
 		"summary": data,
 	})
 
-	for _, devCfg := range cfg.Folders()[folder].Devices {
+	for _, devCfg := range c.cfg.Folders()[folder].Devices {
 		if devCfg.DeviceID.Equals(myID) {
 			// We already know about ourselves.
 			continue