Minor configure updates to make things compile on OSX with openssl 1.0.0 already installed on the system

Conflicts:
	tests/main.c
	tests/spdylay_session_test.c
	tests/spdylay_session_test.h

We use following algorithm to select protocol:

 1. If server's list contains "spdy/2", this function selects
    "spdy/2" and returns 1. The following steps are not taken.

 2. If server's list contains "http/1.1", this function selects
    "http/1.1" and returns 0. The following step is not taken.

 3. This function selects "spdy/2" and returns -1. (So called
    non-overlap case).

This function invoked when request from remote peer is
received.  In other words, frame with FIN flag set is received.  In
HTTP, this means HTTP request, including request body, is fully
received.

If max concurrent streams limit is reached, SYN_STREAM frames are not sent
and backed off. If other type of frame is waiting in the tx queue, it is
sent first. We introduced another priority queue for this purpose.
In this change we did not add code to send RST_STREAM when SYN_STREAM is
received but max concurrent stream is reached.