destination windows were confused, one instead of other.
This error was masked, because first segment of just
established connection is usually smaller than initially
announced window, and it was successfully passed. First
window reannouncement corrected erroneous 'seqhi' value.
The error showed up when client connected to synproxy
with zero initial window, and reannounced it after
session establishment.
In collaboration with: dhartmei [we came to same patch independtly]
Reviewed by: mlaier
Sponsored by: Rambler
MFC after: 3 days
2fa088e969