INTERNALS: remove curlx_tv* functions no longer provided

   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()`

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   returns a struct timeval for the current time.

`curlx_tvdiff()`

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   returns the difference between two timeval structs, in number of

   milliseconds.

`curlx_tvdiff_secs()`

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   returns the same as `curlx_tvdiff` but with full usec resolution (as a

   double)

Future

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