Throughout, change check for running under Windows NT to 'iswinnt'.

* dcrt0.cc (set_os_type): Set 'iswinnt' appropriately.
* cygheap.cc (init_cheap): Revert to using VirtualAlloc for allocating cygheap.
(cygheap_setup_for_child_cleanup): New function.  Standard function to call
after calling CreateProcess to cleanup cygheap info passed to child.
(cygheap_fixup_in_child): Copy cygheap from shared memory into allocated space
under Windows 9x or if can't relocate shared space under NT.
* cygheap.h: Declare new function.
* spawn.cc (spawn_guts): Use cygheap_fixup_in_child.
* fork.cc (fork_parent): Ditto.
* winsup.h: Declare iswinnt.

winsup/cygwin/spawn.cc

@@ -675,7 +675,7 @@ skip_arg_parsing:
   MALLOC_CHECK;
   if (envblock)
     free (envblock);
-  ForceCloseHandle1 (ciresrv.cygheap_h, passed_cygheap_h);
+  cygheap_setup_for_child_cleanup (&ciresrv);
   MALLOC_CHECK;
 
   /* Set errno now so that debugging messages from it appear before our
@@ -718,6 +718,7 @@ skip_arg_parsing:
       strace.execing = 1;
       hExeced = pi.hProcess;
       strcpy (myself->progname, real_path);
+      close_all_files ();
     }
   else
     {