We call on_stream_close_callback even if stream->state is
NGHTTP2_STREAM_INITIAL. This will happen while sending request
HEADERS, a local endpoint receives RST_STREAM for that
stream. It may be PROTOCOL_ERROR, but without notifying stream
closure will hang the stream in a local endpoint.

Also the comment referred to non-existing SPDY defines

Use --dh-param-file option to specify a file including DH parameters
in PEM format.

For example, you can create DH parameters with 1024 bit key using
following command:

$ openssl dhparam -outform PEM -out dhparam.pem 1024

It would be desired to add option to make this limit configurable.
Fix scripted_recv_callback in tests.