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/security.cc

@@ -108,7 +108,7 @@ extern "C"
 HANDLE
 cygwin_logon_user (const struct passwd *pw, const char *password)
 {
-  if (os_being_run != winNT)
+  if (!iswinnt)
     {
       set_errno (ENOSYS);
       return INVALID_HANDLE_VALUE;
@@ -1063,7 +1063,7 @@ static int
 get_nt_attribute (const char *file, int *attribute,
 		  uid_t *uidret, gid_t *gidret)
 {
-  if (os_being_run != winNT)
+  if (!iswinnt)
     return 0;
 
   syscall_printf ("file: %s", file);
@@ -1286,7 +1286,7 @@ alloc_sd (uid_t uid, gid_t gid, const char *logsrv, int attribute,
 {
   BOOL dummy;
 
-  if (os_being_run != winNT)
+  if (!iswinnt)
     return NULL;
 
   if (!sd_ret || !sd_size_ret)
@@ -1557,7 +1557,7 @@ static int
 set_nt_attribute (const char *file, uid_t uid, gid_t gid,
 		  const char *logsrv, int attribute)
 {
-  if (os_being_run != winNT)
+  if (!iswinnt)
     return 0;
 
   DWORD sd_size = 4096;