NGHTTP2_CLIENT_CONNECTION_PREFACE has the same content with
NGHTTP2_CLIENT_CONNECTION_HEADER, which is now obsoleted by
NGHTTP2_CLIENT_CONNECTION_PREFACE.
Supplying multiple URIs can simulate more real life situation on
server side. For example, we can supply URIs of html, css and js and
benchmark the server. The -m option is updated so that it defaults to
the number of supplied URIs.
The profiler and benchmarking showed that calling evbuffer_add()
repeatedly is very costly. To avoid this, we buffer up small writes
into one large chunk and call evbuffer_add() less times.
Tatsuhiro Tsujikawa