HTTP/2 does not require TLS connection, it can work in a cleartext mode.
Plus at the moment only OpenSSL backend allows HTTP/2 negotiation
via ALPN/NPN (and none of our CI configurations with OpenSSL supports
these extensions, rendering HTTP/2 auto-test useless). This patch
implements cleartext HTTP/2 ('h2c') in 'direct' mode - this is
allowed if a client has a prior knowledge that HTTP/2 is supported by
a server.
Change-Id: I4978775e9732c40bc77f549b83bb4a5d1761887e
Reviewed-by: Alex Trotsenko <alex1973tr@gmail.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
69ff49e8f1