The qemu guest agent creates a bunch of files with insecure permissions
when started in daemon mode. For now mask all file mode bits for "group" and "others" in
become_daemon(). Temporarily, for compatibility reasons, stick with the 0666 file-mode in
case of files newly created by the "guest-file-open" QMP call. Do so
without changing the umask temporarily.

QEMU was updated to 1.1.2 on openSUSE 12.2, and 1.3.1 on openSUSE 12.3.