Merge branch 'ab/http-drop-old-curl'

Support for ancient versions of cURL library (pre 7.19.4) has been
dropped.

* ab/http-drop-old-curl:
  http: rename CURLOPT_FILE to CURLOPT_WRITEDATA
  http: drop support for curl < 7.19.3 and < 7.17.0 (again)
  http: drop support for curl < 7.19.4
  http: drop support for curl < 7.16.0
  http: drop support for curl < 7.11.1

diff --cc imap-send.c
Simple merge

diff --cc remote-curl.c
Simple merge