vendor: Update everything

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4620

vendor/github.com/cznic/fileutil/fileutil.go

@@ -190,7 +190,9 @@ func TempFile(dir, prefix, suffix string) (f *os.File, err error) {
 		f, err = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
 		if os.IsExist(err) {
 			if nconflict++; nconflict > 10 {
+				randmu.Lock()
 				rand = reseed()
+				randmu.Unlock()
 			}
 			continue
 		}