Fix integer wraparound on 32-bit machines

Remove unused errno.h include from ngtcp2_log

This causes conn_get_earliest_pktns() to falsely report a nonzero loss time, resulting in spurious retransmissions.

Commit 0999d327 ("Pass user-defined
printf function rather than passing file descriptor") removed the usage
of errno so it does not need to be included.

Remove unused string.h include from examplestest

Remove ngtcp2_conn_get_bytes_in_flight.  Use ngtcp2_conn_get_conn_stat
instead.

Fix assertion failure which occurs when CWND is filled up with
Handshake probe packet and Short packet in the first call of
ngtcp2_conn_writev_stream with NGTCP2_WRITE_STREAM_FLAG_MORE flag set.
The next ngtcp2_conn_writev_stream gets assertion failure.

Fix format specifiers and missing argument passed to log_printf()

Fix format specifier in log_fr_connection_close()

ngtcp2_connection_close.reason_len is size_t, which is not necessarily 64-bit.

Remove transport parameter redundancy check because it causes now
segmentation fault.  The parameter type is now encoded in varint which
does not fit into 16 bits integer anymore.

Simplify remove_tx_stream_data()

The return value from this function is not used.

This prioritizes Handshake probe packet over Short probe if both data
are outstanding.

This is a deviation from draft-27 recovery draft.

This prevents Handshake probe packet from being sent even if Handshake
packet number space has no outstanding data to send.

This is a deviation from draft-27 recovery draft.

This reverts commit f738004f.

This prevents Handshake probe packet from being sent even if Handshake
packet number space has no outstanding data to send.

This is a deviation from draft-27 recovery draft.

Fix coalesced 0-RTT ACK packet with short header packet