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/net.cc

@@ -122,7 +122,7 @@ WSADATA wsadata;
 static SOCKET __stdcall
 set_socket_inheritance (SOCKET sock)
 {
-  if (os_being_run == winNT)
+  if (iswinnt)
     (void) SetHandleInformation ((HANDLE) sock, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT);
   else
     {
@@ -1292,9 +1292,9 @@ getdomainname (char *domain, int len)
    * Punt for now and assume MS-TCP on Win95.
    */
   reg_key r (HKEY_LOCAL_MACHINE, KEY_READ,
-	     (os_being_run != winNT) ? "System" : "SYSTEM",
+	     (!iswinnt) ? "System" : "SYSTEM",
 	     "CurrentControlSet", "Services",
-	     (os_being_run != winNT) ? "MSTCP" : "Tcpip",
+	     (!iswinnt) ? "MSTCP" : "Tcpip",
 	     NULL);
 
   /* FIXME: Are registry keys case sensitive? */