Remove atexit() call on Win32 code path that cause crashes on mapserv

Reported on http://lists.osgeo.org/pipermail/mapserver-dev/2014-October/014269.html
The cleanup done by the atexit() callback is redundant with the one done
by msCleanup(0) at the end of the main().

Author: rouault

mapserv.c

@@ -234,10 +234,6 @@ int main(int argc, char *argv[])
 #ifdef USE_FASTCGI
   msIO_installFastCGIRedirect();
 
-#ifdef WIN32
-  atexit( msCleanupOnExit );
-#endif
-
   /* In FastCGI case we loop accepting multiple requests.  In normal CGI */
   /* use we only accept and process one request.  */
   while( FCGI_Accept() >= 0 ) {