SMBIOS: Update Type 0 struct generator for machines >= 2.1

SMBIOS: Update Type 0 struct generator for machines >= 2.1

Update how type 0 (bios info) structures are generated, as follows:

  - convert bios_characteristics field to uin64_t (instead of
    uint8_t[8]), as described in the current smbios spec (v2.8)

  - enable "virtual machine" bit in bios_characteristics_extension_bits

  - add command line option to enable "uefi supported" bit in
    bios_characteristics_extension_bits

These updates should make this optional structure more useful when
used with edk2/ovmf. Only pc machines >= 2.1 are affected, and only
when a type 0 structure is explicitly specified on the command line.

Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>