Fix previous mode detection by reading CS from the trap frame

xtoskrnl/ar/i686/archsup.S

@@ -111,7 +111,7 @@ _Ar\Type\Vector\()Start:
 
         /* Test previous mode and swap GS if needed */
         movl $0, TrapPreviousMode(%ebp)
-        mov %cs, %ax
+        mov TrapSegCs(%ebp), %ax
         and $3, %al
         mov %al, TrapPreviousMode(%ebp)
         jz KernelMode\Type\Vector

xtoskrnl/includes/ar/i686/asmsup.h

@@ -25,6 +25,7 @@
 #define TrapSegFs                               40
 #define TrapSegGs                               42
 #define TrapVector                              72
+#define TrapSegCs                               84
 #define TrapEsp                                 92
 #define TrapSegSs                               96