Merge branch 'ew/http-do-not-forget-to-call-curl-multi-remove-handle'

The http transport (with curl-multi option, which is the default these days) failed to remove curl-easy handle from a curlm session, which led to unnecessary API failures. * ew/http-do-not-forget-to-call-curl-multi-remove-handle: http: always remove curl easy from curlm session on release http: consolidate #ifdefs for curl_multi_remove_handle http: warn on curl_multi_add_handle failures