ACK frame largest_ack field is always the largest packet number even
if the ACK that contains largest_ack has been acknowledged by a remote
endpoint.

Remove Requires field because it breaks application build which checks TLS library independently.

This commit fixes the assertion failure which happens when
acknowledgement of earlier packet increases CRYPTO offset.
Previously, the offset is always the first CRYPTO frame offset in the
queue (pktns->crypto.tx.frq).  But passing this into
ngtcp2_pkt_crypto_max_datalen() underestimates the space because
acknowledgement might increase offset; it increases the required space
to serialize offset.

Remove unused parameter from generate_token_aad()

Fix MSVC build

The ngtcp2_cc.c file was using the __builtint_clzll intrinsic which
doesn't exist on MSVC. Added use of the corresponding __lzcnt
intrinsics.

Fix buffer overflow in conn_on_version_negotiation()

This reverts commit 7c611382.

Don't reset cstat->last_tx_pkt_ts which makes assert(earliest_pktns)
fail.

Fully initialize ngtcp2_transport_params