Win32 gettimeofday() comment patch

Add a note to Win32 gettimeofday() emulation.

Regards,
Qingqing

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Index: gettimeofday.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/port/gettimeofday.c,v
retrieving revision 1.6
diff -c -r1.6 gettimeofday.c
*** gettimeofday.c      16 May 2005 05:52:13 -0000      1.6
--- gettimeofday.c      16 Dec 2005 19:37:41 -0000
***************
*** 36,41 ****
--- 36,43 ----

  /*
   * timezone information is stored outside the kernel so tzp isn't used anymore.
+  * Note: this function is not for Win32 high precision timing purpose, see
+  * elapsed_time() etc.
   */
  int
  gettimeofday(struct timeval * tp, struct timezone * tzp)