event: Add support for non blocking behaviour in the
CONN_STATE_READ_REQUEST_LINE phase, in addition to the existing
CONN_STATE_WRITE_COMPLETION phase. Update mod_ssl to perform non blocking
TLS handshakes.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1897281 13f79535-47bb-0310-9956-ffa450edef68
