smbios: filter based on CONFIG_SMBIOS rather than TARGET

-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: Leif Lindholm <leif.lindholm@linaro.org>
Message-Id: <20161222151828.28292-1-leif.lindholm@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/smbios/smbios-stub.c

@@ -0,0 +1,31 @@
+/*
+ * SMBIOS stubs for platforms that don't support SMBIOS.
+ *
+ * Copyright (c) 2010 Isaku Yamahata <yamahata at valinux co jp>
+ *                    VA Linux Systems Japan K.K.
+ * Copyright (c) 2016 Leif Lindholm <leif.lindholm@linaro.org>
+ *                    Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/qmp/qerror.h"
+#include "qmp-commands.h"
+#include "hw/smbios/smbios.h"
+
+void smbios_entry_add(QemuOpts *opts, Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+}