Add missing va_end() to xasprintf() in grub-emu.

Author: pbatard

grub-core/kern/emu/misc.c

@@ -127,6 +127,7 @@ xasprintf (const char *fmt, ...)
 
   va_start (ap, fmt);
   result = grub_xvasprintf (fmt, ap);
+  va_end (ap);
   if (!result)
     grub_util_error ("%s", _("out of memory"));