file until it is actually being uploaded.
Make sure we build and still work with HTTP disabled - the SSL code might use
the boundary string for some random seeding.

might be used uninitialized

a host name that resolves to multiple IP addresses.

path after a transfer.

--disable-http, which thus builds a libcurl without HTTP support.

keep the API complete at all times

Setting CURLOPT_RESUME_FROM to 0 prevents a resumed transfer.

An Alexander Krasnostavsky fix.

if one transfer fails.