tommink[at]post.pl reported in bug report #1337723

(http://curl.haxx.se/bug/view.cgi?id=1337723) that curl could not upload
binary data from stdin on Windows if the data contained control-Z (hex 1a)
since that is treated as end-of-file when read in text mode. Gisle Vanem
pointed out the fix, and I made both -T and --data-binary take advantage of
it.