pgsql: Check for STATUS_DELETE_PENDING on Windows.

Check for STATUS_DELETE_PENDING on Windows.

1. Update our open() wrapper to check for NT's STATUS_DELETE_PENDING
and translate it to Unix-like errors. This is done with
RtlGetLastNtStatus(), which is dynamically loaded from ntdll. A new
file win32ntdll.c centralizes lookup of NT functions, in case we decide
to add more in the future.

2. Remove non-working code that was trying to do something similar for
stat(), and just reuse the open() wrapper code. As a side effect,
stat() also gains resilience against "sharing violation" errors.

3. Since stat() is used very early in process startup, remove the
requirement that the Win32 signal event has been created before
pgwin32_open_handle() is reached. Instead, teach pg_usleep() to fall
back to a non-interruptible sleep if reached before the signal event is
available.

This could be back-patched, but for now it's in master only. The
problem has apparently been with us for a long time and generated only a
few complaints. Proposed patches trigger it more often, which led to
this investigation and fix.

Reviewed-by: Andres Freund <andres(at)anarazel(dot)de>
Reviewed-by: Alexander Lakhin <exclusion(at)gmail(dot)com>
Reviewed-by: Juan José Santamaría Flecha <juanjo(dot)santamaria(at)gmail(dot)com>
Discussion: https://postgr.es/m/CA%2BhUKGJz_pZTF9mckn6XgSv69%2BjGwdgLkxZ6b3NWGLBCVjqUZA%40mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/e2f0f8ed251d02c1eda79e1ca3cb3db2681e7a86

Modified Files
--------------
configure | 6 ++
configure.ac | 1 +
src/backend/port/win32/signal.c | 12 ++-
src/include/port.h | 1 +
src/include/port/win32ntdll.h | 27 +++++++
src/port/open.c | 104 +++++++++++++------------
src/port/win32ntdll.c | 69 +++++++++++++++++
src/port/win32stat.c | 164 ++--------------------------------------
src/tools/msvc/Mkvcbuild.pm | 3 +-
9 files changed, 178 insertions(+), 209 deletions(-)