Passing `-M microvm` and `-smbios type=11...` results in smbios args being silently dropped

Host environment

Operating system: Nixos
OS/kernel version: 6.12.12
Architecture: x86
QEMU flavor: qemu-system-x86_64
QEMU version: 9.2.0

QEMU command line:

./qemu-system-x86_64 -M microvm -smbios type=11,value=io.systemd.credential:mycred=supersecret

Emulated/Virtualized environment

Operating system: nixos
OS/kernel version: 6.12.12
Architecture: x86

Description of problem

(reporting as requested by danpb on IRC)

Using the -machine microvm flag with the smbios type=11... argument results in the smbios options being silently discarded, because the microvm target doesn't seem to support the smbios feature.

danpb on IRC suggested that passing those two incompatible flags should result in an error.

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