3484 enhance and document tail follow support
Reviewed by: Joshua M. Clulow <jmc@joyent.com>

*** 22,36 ****
  /*
   * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
  #ifndef _SYS_PORT_H
  #define _SYS_PORT_H
  
- #pragma ident   "%Z%%M% %I%     %E% SMI"
- 
  #ifdef  __cplusplus
  extern "C" {
  #endif
  
  #include <sys/types.h>
--- 22,38 ----
  /*
   * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
+ /*
+  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
+  */
+ 
  #ifndef _SYS_PORT_H
  #define _SYS_PORT_H
  
  #ifdef  __cplusplus
  extern "C" {
  #endif
  
  #include <sys/types.h>
*** 104,113 ****
--- 106,116 ----
   * User watchable file events
   */
  #define FILE_ACCESS             0x00000001
  #define FILE_MODIFIED           0x00000002
  #define FILE_ATTRIB             0x00000004
+ #define FILE_TRUNC              0x00100000
  #define FILE_NOFOLLOW           0x10000000
  
  /*
   * exception file events
   */