careful with ureg padding

Reference: /n/atom/patch/applied/realemuureg
Date: Thu Jun 12 21:10:58 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/aux/realemu/loadcom.c	Thu Jun 12 21:10:58 2014
+++ /sys/src/cmd/aux/realemu/loadcom.c	Thu Jun 12 21:10:58 2014
@@ -1,7 +1,9 @@
 #include <u.h>
 #include <libc.h>
 
+#pragma pack on
 #include "/386/include/ureg.h"
+#pragma pack off
 
 static uchar buf[0xFF01];