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