local: Ignore ENOTSUP error for chmod

Closes: #1079

src/restic/backend/local/local_unix.go

@@ -5,9 +5,15 @@ package local
 import (
 	"os"
 	"restic/fs"
+	"syscall"
 )
 
 // set file to readonly
 func setNewFileMode(f string, fi os.FileInfo) error {
-	return fs.Chmod(f, fi.Mode()&os.FileMode(^uint32(0222)))
+	err := fs.Chmod(f, fi.Mode()&os.FileMode(^uint32(0222)))
+	// ignore the error if the FS does not support setting this mode (e.g. CIFS with gvfs on Linux)
+	if err == syscall.ENOTSUP {
+		err = nil
+	}
+	return err
 }