qemu-config: restore "machine" in qmp_query_command_line_options()

Commit d8fb7d0 ("vl: switch -M parsing
to keyval") stopped adding the "machine" QemuOptsList. This causes
"machine" options to not show up in QMP query-command-line-options
output. For example, libvirt cannot detect that kernel_irqchip support
is available.

Adjust the "machine" opts enumeration in
qmp_query_command_line_options() so that options are properly reported.

Fixes: d8fb7d0 ("vl: switch -M parsing to keyval")
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210721151055.424580-1-stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

util/qemu-config.c

@@ -255,8 +255,6 @@ CommandLineOptionInfoList *qmp_query_command_line_options(bool has_option,
             info->option = g_strdup(vm_config_groups[i]->name);
             if (!strcmp("drive", vm_config_groups[i]->name)) {
                 info->parameters = get_drive_infolist();
-            } else if (!strcmp("machine", vm_config_groups[i]->name)) {
-                info->parameters = query_option_descs(machine_opts.desc);
             } else {
                 info->parameters =
                     query_option_descs(vm_config_groups[i]->desc);
@@ -265,6 +263,13 @@ CommandLineOptionInfoList *qmp_query_command_line_options(bool has_option,
         }
     }
 
+    if (!has_option || !strcmp(option, "machine")) {
+        info = g_malloc0(sizeof(*info));
+        info->option = g_strdup("machine");
+        info->parameters = query_option_descs(machine_opts.desc);
+        QAPI_LIST_PREPEND(conf_list, info);
+    }
+
     if (conf_list == NULL) {
         error_setg(errp, "invalid option name: %s", option);
     }