Fix handling of SETTINGS_MAX_CONCURRENT_STREAMS.

Remove remaining SPDY code from the integration tests.

The maximum number of outgoing concurrent streams is initially
limited to 100 to avoid issues when the local endpoint submits
lots of requests before receiving initial SETTINGS frame from
the remote endpoint, since sending them at once to the remote
endpoint could lead to rejection of some of the requests.

This initial limit is overwritten with the value advertised in
SETTINGS_MAX_CONCURRENT_STREAMS setting by the remote endpoint,
but previously, it wasn't lifted if the remote endpoint didn't
advertise that setting (implying no limits), in which case the
limit of 100 was retained, even though it was never advertised
by the remote endpoint.
Signed-off-by: Piotr Sikora <piotrsikora@google.com>

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

ORIGIN frame

asio: Support client side SNI

h2load: -r and --duration are mutually exclusive

Libressl

LIBRESSL_LEGACY_API is drop-in replacement for LIBRESSL_IN_USE.  In
the upcoming commits, we will add changes to support libressl 2.7.

NPN has been superseeded by ALPN. OpenSSL provides a configure
option to disable npn (no-npn) which results in an OpenSSL
installation that defines OPENSSL_NO_NEXTPROTONEG in opensslconf.h

The #ifdef's look safe here (as the next_proto is initialized as
nullptr). Alteratively, macros could be defined for the used npn
methods that return a 0 for next_proto.
Signed-off-by: Bernard Spil <brnrd@FreeBSD.org>