tests/cdrom-test: Test booting from CD-ROM ISO image file

tests/cdrom-test: Test booting from CD-ROM ISO image file

We already have the code for a boot file in tests/boot-sector.c,
so if the genisoimage program is available, we can easily create
a bootable CD ISO image that we can use for testing whether our
CD-ROM emulation and the BIOS CD-ROM boot works correctly.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Hervé Poussineau <hpoussin@reactos.org>
Acked-By: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>