pg_upgrade: properly detect file copy failure on Windows

Previously, file copy failures were ignored on Windows due to an
incorrect return value check.

Report by Manu Joye

Backpatch through 9.1

contrib/pg_upgrade/file.c

@@ -38,7 +38,11 @@ copyAndUpdateFile(pageCnvCtx *pageConverter,
 {
 	if (pageConverter == NULL)
 	{
-		if (pg_copy_file(src, dst, force) == -1)
+#ifndef WIN32
+		if (copy_file(src, dst, force) == -1)
+#else
+		if (CopyFile(src, dst, force) == 0)
+#endif
 			return getErrorText(errno);
 		else
 			return NULL;

contrib/pg_upgrade/pg_upgrade.h

@@ -35,7 +35,6 @@
 #define DB_DUMP_FILE		"pg_upgrade_dump_db.sql"
 
 #ifndef WIN32
-#define pg_copy_file		copy_file
 #define pg_mv_file			rename
 #define pg_link_file		link
 #define PATH_SEPARATOR      '/'
@@ -43,7 +42,6 @@
 #define RMDIR_CMD			"rm -rf"
 #define SCRIPT_EXT			"sh"
 #else
-#define pg_copy_file		CopyFile
 #define pg_mv_file			pgrename
 #define pg_link_file		win32_pghardlink
 #define sleep(x)			Sleep(x * 1000)