mprintf: Replaced internal usage of FORMAT_OFF_T and FORMAT_OFF_TU

Following commit 0aafd77fa4, replaced the internal usage of
FORMAT_OFF_T and FORMAT_OFF_TU with the external versions that we
expect API programmers to use.

This negates the need for separate definitions which were subtly
different under different platforms/compilers.

lib/multi.c

@@ -986,7 +986,8 @@ static CURLMcode multi_runsingle(struct Curl_multi *multi,
         else {
           k = &data->req;
           failf(data, "Operation timed out after %ld milliseconds with %"
-                FORMAT_OFF_T " out of %" FORMAT_OFF_T " bytes received",
+                CURL_FORMAT_CURL_OFF_T " out of %"
+                CURL_FORMAT_CURL_OFF_T " bytes received",
                 Curl_tvdiff(now, data->progress.t_startsingle), k->bytecount,
                 k->size);
         }