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

Node.js makes the full `ngtcp2_transport_params` struct available
for storage as a byte array, including any possible padding
in the struct.

Fully initializing the struct with `memset()` makes this deterministic.