CURLOPT_COPYPOSTFIELDS with a given CURLOPT_POSTFIELDSIZE does not
require a trailing zero of the data and by making sure this test doesn't
use one we know it works (combined with valgrind).
Do not try to convert line-endings to CRLF on Windows by setting stdout
to binary mode, just like the curl tool does if --ascii is not specified.
This should prevent corrupted stdout line-ending output like CRCRLF.
In order to make the previously naive text-aware tests work with
binary mode on Windows, text-mode is disabled for them if it is not
actually part of the test case and line-endings are corrected.
