-smbios command line options were accepted but silently ignored on
TARGET_ARM, due to a test for TARGET_I386 in arch_init.c.

Copy the mechanism of hw/pci/pci-stub.c to implement an smbios-stub
instead, enabled for all targets without CONFIG_SMBIOS.
Signed-off-by: NLeif Lindholm <leif.lindholm@linaro.org>
Message-Id: <20161222151828.28292-1-leif.lindholm@linaro.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>