If using the read callback for HTTP_POST, and POSTFIELDSIZE is not set,
automatically add a Transfer-Encoding: chunked header, same as it is
already done for HTTP_PUT, HTTP_POST_FORM and HTTP_POST_MIME. Update
test 1514 according to the new behaviour.
Closes#4138
According to RFC 2616 and RFC 2326 individual protocol elements, like
headers and except the actual content, are terminated by using CRLF.
Therefore the test data files for these protocols need to contain
mixed line-endings if the actual protocol elements use CRLF while
the file uses LF.
