windows: Set UMDF_USING_NTSTATUS globally, include ntstatus.h

We'd like to use precompiled headers on windows to reduce compile times. Right
now we rely on defining UMDF_USING_NTSTATUS before including postgres.h in a few
select places - which doesn't work with precompiled headers.  Instead define
it globally.

When UMDF_USING_NTSTATUS is defined we need to explicitly include ntstatus.h,
winternl.h to get a comparable set of symbols. Right now these includes would
be required in a number of non-platform-specific .c files - to avoid that,
include them in win32_port.h. Based on my measurements that doesn't increase
compile times measurably.

Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20220927011951.j3h4o7n6bhf7dwau@awork3.anarazel.de

src/include/port/win32_port.h

@@ -48,12 +48,21 @@
  * significantly.  WIN32_LEAN_AND_MEAN reduces that a bit. It'd be better to
  * remove the include of windows.h (as well as indirect inclusions of it) from
  * such a central place, but until then...
+ *
+ * To be able to include ntstatus.h tell windows.h to not declare NTSTATUS by
+ * temporarily defining UMDF_USING_NTSTATUS, otherwise we'll get warning about
+ * macro redefinitions, as windows.h also defines NTSTATUS (yuck). That in
+ * turn requires including ntstatus.h, winternl.h to get common symbols.
  */
 #define WIN32_LEAN_AND_MEAN
+#define UMDF_USING_NTSTATUS
 
 #include <winsock2.h>
 #include <ws2tcpip.h>
 #include <windows.h>
+#include <ntstatus.h>
+#include <winternl.h>
+
 #undef small
 #include <process.h>
 #include <signal.h>