Bring back LX zones.

*** 629,638 ****
--- 629,668 ----
          popl    %ecx                    / sysexit: %ecx -> %esp
          sti
          sysexit
          SET_SIZE(sys_sysenter)
          SET_SIZE(brand_sys_sysenter)
+ #endif  /* __lint */
+ 
+ #if defined(__lint)
+ /*
+  * System call via an int80.  This entry point is only used by the Linux
+  * application environment.  Unlike the sysenter path, there is no default
+  * action to take if no callback is registered for this process.
+  */
+ void
+ sys_int80()
+ {}
+ 
+ #else   /* __lint */
+ 
+         ENTRY_NP(brand_sys_int80)
+         BRAND_CALLBACK(BRAND_CB_INT80)
+ 
+         ALTENTRY(sys_int80)
+         /*
+          * We hit an int80, but this process isn't of a brand with an int80
+          * handler.  Bad process!  Make it look as if the INT failed.
+          * Modify %eip to point before the INT, push the expected error
+          * code and fake a GP fault.
+          * 
+          */
+         subl    $2, (%esp)      /* int insn 2-bytes */
+         pushl   $_CONST(_MUL(T_INT80, GATE_DESC_SIZE) + 2)
+         jmp     gptrap                  / GP fault
+         SET_SIZE(sys_int80)
+         SET_SIZE(brand_sys_int80)
  
  /*
   * Declare a uintptr_t which covers the entire pc range of syscall
   * handlers for the stack walkers that need this.
   */