Set 'native-comp-debug' to zero on MS-Windows

Set 'native-comp-debug' to zero on MS-Windows

* lisp/emacs-lisp/comp.el (native-comp-debug): Don't emit debug
symbols on MS-Windows.  The default was originally made 1 because
without that, C backtraces on Windows would not show
natively-compiled functions correctly, or would even stop short of
reaching the topmost call frame.  But that turned out to be due to
a bug in GDB, which was meanwhile fixed in GDB 12.  So we can now
reset the value back to zero, and gain smaller *.eln files on
MS-Windows.