vl, pc: turn -no-fd-bootchk into a machine property

Add a fd-bootchk property to PC machine types, so that -no-fd-bootchk
returns an error if the machine does not support booting from floppies
and checking for boot signatures therein.

Suggested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
5 files changed