multi & hiper examples: updates and cleanups

all multi and hiper examples:

* don't loop curl_multi_perform calls, that was <7.20.0 style, currently
  the exported multi functions will not return CURLM_CALL_MULTI_PERFORM

all hiper examples:
* renamed check_run_count to check_multi_info
* don't  compare current running handle count with previous value, this
  was the wrong way to check for finished requests, simply call
  curl_multi_info_read
* it's also safe to call curl_multi_remove_handle inside the
  curl_multi_info_read loop.

ghiper.c:
* replaced curl_multi_socket (that function is marked as obsolete) calls
  with curl_multi_socket_action calls (as in hiperfifo.c and
  evhiperfifo.c)

ghiper.c and evhiperfifo.c:
* be smart as hiperfifo.c, don't do uncessary curl_multi_* calls in
  new_conn and main