Clarify path parameter in path_validation comment

Minor correction in bound_dcids comment

This commit attempts to clarify the path parameter to be clear that this
is the path that was validated. Currently this can give the impression
that the callback should validate this path, but my understanding is
that the actual path validation is done by ngtcp2_pv_validate.

Fix Windows builds

Fix typo in conn_recv_handshake_pkt comment

Remove unnecessary semicolon in ngtcp2_crypto.c

Fix typo in tp_file comment