qemu-options: Allow -no-user-config again

After 1217d6ca2b we error out
explicitly if an unknown -option was passed on the command line.
However, we are doing two pass command line option parsing. In
the first pass we just look for -no-user-config or -nodefconfig
being present which determines whether we load user config or
not. Then in the second pass we finally parse everything else
throwing an error if an unsupported -option was found. Problem is
that in the second pass -no-user-config and -nodefconfig are not
handled explicitly which makes us throw the unsupported option
error.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

vl.c

@@ -4011,6 +4011,10 @@ int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_nodefconfig:
+            case QEMU_OPTION_nouserconfig:
+                /* Nothing to be parsed here. Especially, do not error out below. */
+                break;
             default:
                 if (os_parse_cmd_args(popt->index, optarg)) {
                     error_report("Option not supported in this build");