11859 need swapgs mitigation
Reviewed by: Robert Mustacchi <rm@fingolfin.org>
Reviewed by: Dan McDonald <danmcd@joyent.com>
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Robert Mustacchi <rm@fingolfin.org>

*** 1,10 ****
  /*
   * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
   */
  /*
!  * Copyright 2018 Joyent, Inc.
   */
  
  #ifndef _SYS_SEGMENTS_H
  #define _SYS_SEGMENTS_H
  
--- 1,10 ----
  /*
   * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
   */
  /*
!  * Copyright 2019 Joyent, Inc.
   */
  
  #ifndef _SYS_SEGMENTS_H
  #define _SYS_SEGMENTS_H
  
*** 177,187 ****
   */
  extern void __set_ds(selector_t);
  extern void __set_es(selector_t);
  extern void __set_fs(selector_t);
  extern void __set_gs(selector_t);
- extern void __swapgs(void);
  #endif  /* __amd64 */
  
  #if defined(__amd64)
  extern void load_segment_registers(selector_t, selector_t, selector_t,
      selector_t);        /* (alphabetical) */
--- 177,186 ----