Chmod error should not be fatal (fixes #612)

cmd/syncthing/main.go

@@ -1003,7 +1003,10 @@ func ensureDir(dir string, mode int) {
 		l.FatalErr(err)
 	} else if mode >= 0 && err == nil && int(fi.Mode()&0777) != mode {
 		err := os.Chmod(dir, os.FileMode(mode))
-		l.FatalErr(err)
+		// This can fail on crappy filesystems, nothing we can do about it.
+		if err != nil {
+			l.Warnln(err)
+		}
 	}
 }