strtoll() (or equivalent) function exist on your platform. If `curl_off_t`
is only a 32 bit number on your platform, this macro uses strtol().
-`curlx_tvnow()`
----------------
- returns a struct timeval for the current time.
-
-`curlx_tvdiff()`
---------------
- returns the difference between two timeval structs, in number of
- milliseconds.
-
-`curlx_tvdiff_secs()`
----------------------
- returns the same as `curlx_tvdiff` but with full usec resolution (as a
- double)
-
Future
------