Remove mingwcompat.c

We believe that the issues that this was working around have been
fixed in MinGW more than 5 years ago, so this isn't necessary anymore.

Discussion: https://www.postgresql.org/message-id/flat/20190719050830.GK1859%40paquier.xyz

src/backend/port/win32/Makefile

@@ -12,7 +12,7 @@ subdir = src/backend/port/win32
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = timer.o socket.o signal.o mingwcompat.o
+OBJS = timer.o socket.o signal.o
 ifeq ($(have_win32_dbghelp), yes)
 OBJS += crashdump.o
 endif

src/backend/port/win32/mingwcompat.c

-/*-------------------------------------------------------------------------
- *
- * mingwcompat.c
- *	  MinGW compatibility functions
- *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
- *
- * IDENTIFICATION
- *	  src/backend/port/win32/mingwcompat.c
- *
- *-------------------------------------------------------------------------
- */
-
-#include "postgres.h"
-
-#ifndef _MSC_VER
-/*
- * MingW defines an extern to this struct, but the actual struct isn't present
- * in any library. It's trivial enough that we can safely define it
- * ourselves.
- */
-const struct in6_addr in6addr_any = {{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}};
-
-
-/*
- * This file contains loaders for functions that are missing in the MinGW
- * import libraries. It's only for actual Win32 API functions, so they are
- * all present in proper Win32 compilers.
- */
-static HMODULE kernel32 = NULL;
-
-/*
- * Load DLL file just once regardless of how many functions
- * we load/call in it.
- */
-static void
-LoadKernel32()
-{
-	if (kernel32 != NULL)
-		return;
-
-	kernel32 = LoadLibraryEx("kernel32.dll", NULL, 0);
-	if (kernel32 == NULL)
-		ereport(FATAL,
-				(errmsg_internal("could not load kernel32.dll: error code %lu",
-								 GetLastError())));
-}
-
-
-/*
- * Replacement for RegisterWaitForSingleObject(), which lives in
- * kernel32.dll
- */
-typedef
-BOOL		(WINAPI * __RegisterWaitForSingleObject)
-			(PHANDLE, HANDLE, WAITORTIMERCALLBACK, PVOID, ULONG, ULONG);
-static __RegisterWaitForSingleObject _RegisterWaitForSingleObject = NULL;
-
-BOOL		WINAPI
-RegisterWaitForSingleObject(PHANDLE phNewWaitObject,
-							HANDLE hObject,
-							WAITORTIMERCALLBACK Callback,
-							PVOID Context,
-							ULONG dwMilliseconds,
-							ULONG dwFlags)
-{
-	if (_RegisterWaitForSingleObject == NULL)
-	{
-		LoadKernel32();
-
-		_RegisterWaitForSingleObject = (__RegisterWaitForSingleObject)
-			GetProcAddress(kernel32, "RegisterWaitForSingleObject");
-
-		if (_RegisterWaitForSingleObject == NULL)
-			ereport(FATAL,
-					(errmsg_internal("could not locate RegisterWaitForSingleObject in kernel32.dll: error code %lu",
-									 GetLastError())));
-	}
-
-	return (_RegisterWaitForSingleObject)
-		(phNewWaitObject, hObject, Callback, Context, dwMilliseconds, dwFlags);
-}
-
-#endif