http_client_req() was supposed to return the number of bytes sent as a
HTTP request. The return value was not riht however due to some bugs in
helper functions:
* http_send_data() returned the current buffer position istead of the
number of bytes actually sent. This could result in counting the same
data into the total request size several times. A helper variable was
added to track how many bytes were actually sent to the network.
* http_flush_data() forwarded the return value of sendall() helper
function. That function however did not return number of bytes sent,
but 0 or a negative error code.
Additionally, change the return type of sendall() function - according
to standard the ssize_t type is only capable of holding -1 negative
value, but the function could return the full range of negative errno
values. Use int instead.
Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
ffdc621f1b