com32/cmenu/adv_menu.tpl: Use the proper value for ipappend

If x is NULL, we're supposed to pass 0 for ipappend; this was
incorrect in the template and the gcc 4.6 unused variable warning
caught it.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

com32/cmenu/adv_menu.tpl

@@ -312,7 +312,7 @@ void runcommand(pt_menuitem mi)
    x = (pt_xtra) mi->extra_data;
    ipappend = (x ? x->ipappend : 0);
 
-   runsyslinuximage(line,x->ipappend);
+   runsyslinuximage(line,ipappend);
    free(line);
 }