Improving Emacs performance on Cygwin

[Ken Brown <kbrown@cornell.edu>]

I would like to apply the following patch, which seems to give a 
substantial performance improvement on Cygwin (and obviously has no 
effect on other platforms).

=== modified file 'src/dired.c'
--- src/dired.c 2010-07-25 00:20:51 +0000
+++ src/dired.c 2010-07-26 20:49:34 +0000
@@ -72,8 +72,7 @@
  #endif /* not MSDOS */
  #endif /* not SYSV_SYSTEM_DIR */

-/* Some versions of Cygwin don't have d_ino in `struct dirent'.  */
-#if defined(MSDOS) || defined(__CYGWIN__)
+#ifdef MSDOS
  #define DIRENTRY_NONEMPTY(p) ((p)->d_name[0] != 0)
  #else
  #define DIRENTRY_NONEMPTY(p) ((p)->d_ino)

This reverses a change made by Eli on 2006-01-27.  Rationale: The time 
when Cygwin didn't have d_ino in dirent was a brief period around 
December 2005, and it applied only to Cygwin 1.5.19, which has long been 
obsolete.

Any objections?  If not, I would apply it to the emacs-23 branch and let 
it propagate to the trunk.

Ken