The on_ctrl_not_send_callback, on_ctrl_recv_parse_error_callback and
on_unknown_ctrl_recv_callback were added. The latter 2 callbacks are
purely debugging purpose. In on_ctrl_not_send_callback, If sending
SYN_REPLY failed, issue RST_STREAM to avoid a stream hanging around.
To distinguish the to-be-installed programs and non-installable
example source code, the former programs, spdycat, spdydyd and shrpx,
were moved to src directory. spdynative was removed from Makefile
because it does not appeal to any users much.