curl_easy_perform: fix timeout handling

curl_easy_perform: fix timeout handling

curl_multi_wait() was erroneously used from within
curl_easy_perform(). It could lead to it believing there was no socket
to wait for and then instead sleep for a while instead of monitoring the
socket and then miss acting on that activity as swiftly as it should
(causing an up to 1000 ms delay).

Reported-by: Antoni Villalonga
Fixes #3305
Clodes #3306

Backported patch details:
https://github.com/curl/curl/commit/d04cef9ce1d710902d90b62de01115b9bbe958bf.patch

Change-Id: I08d95e996dd9bab5d9fd7c7fe581fdb40c8a0de8
Signed-off-by: Niraj Kumar Goit <niraj.g@samsung.com>