bug: Fixing runtime issue with test_util_file.c in Windows

bug: Fixing runtime issue with test_util_file.c in Windows

Windows was failing tests due to how the Windows API works with some of the calls used.
When opening and reading a file O_BINARY is needed otherwise it fails for size checks. This is due to how Windows handles newlines and counts between text and binary mode file reads.

Also fixed is the test for /dev/null.
In Windows, this fails, but crashes due to a missing return statement when it cannot open this file.
I also tried telling windows to open the special file NUL, however that leads to a CRT crash later in the test that cannot be stopped and will always fail. Rather than fail a test that Windows will always fail, it has been disabled in that specific case.

Signed-off-by: Tyler Erickson <tyler.erickson@seagate.com>