Locking files for CLASH_DETECTION now supported on MS-Windows

[Eli Zaretskii]

Trunk revision 111877 implements file locking and clash detection for
MS-Windows (see the node "Interlocking" in the Emacs manual for the
details), so that the related features now work on Windows like they
do on Posix platforms.

After you update from bzr, and compile Emacs, I suggest to
byte-compile files.el and userlock.el, and re-dump Emacs, because
otherwise Emacs might "remember" that it didn't have the primitives
for file locking implemented (they are 'ignore'd away in files.el).

If you don't like interlocking for some reason, you can get the old
behavior back by resetting create-lockfiles to nil.

Enjoy.