By default, configuration file is /etc/shrpx/shrpx.conf.  It can be
overridden using --conf option. See shrpx.conf.sample to know how to
write shrpx.conf. The configurations given in shrpx.conf will be
overridden by the options specified in cmmand-line.

--pid-file option saves PID to the specified file.  user option is
--used to drop root privileges.

Include config.h from sources under examples.  Added kevent.udata type
check.

It seems that specifying NULL to bufferevent_set_timeouts() does not
remove timeout, which is described in bufferevent book (but it is not
described in header). As a workaround, we specify long enough timeout
to emulate removing timeout.

Chrome SPDY/3 flow control does not work well in spdy proxy
connection.

Log error string in case of network error

For upstream timeout, it seems OpenSSL backed bufferevent does not
remove timeout. Set large timeout as a workaround.

Jetty refuses connection if SSLv23_client_method is used.

This is just a sanity check in caes of path contains absoluteURI.

This option append X-Forwarded-For header field to the downstream
request.