WP_HTTP: Return error responses from cURL for non-blocking requests. Contrary to popular belief, cURL's non-blocking requests are not exact non-blocking, we still wait for cURL to make the request before returning, so making this change aids in development debugging. Props SergeyBiryukov Fixes #23310


git-svn-id: http://core.svn.wordpress.org/trunk@23607 1a063a9b-81f0-0310-95a4-ce76da25c4cd