incorporate patches for sliding window support

Looks like there may be some issue with the patches as I have been able to create reproducible hangs copying large (750M) files with the patched GVFS packages. This has been reported upstream. Will update this report when it's been resolved.

Thank your bug report, some questions:
- could you explain what "sliding window support" mean and why we want it?
- what's the bug reference for the hang issue?

The addition of sliding window support makes gvfs sftp transfers behave more like openssh sftp file transfers, resulting a significant throughput increase for connections with moderate to high latency (see below).

The hang is being handled within one of the original bug reports, specifically:
https://bugzilla.gnome.org/show_bug.cgi?id=532951.

I'm testing updated patches to see if they resolve the hang.

From the referenced bug reports:
== PULL ==
Some benchmark figures:
Old behavior:
Copying from local server = 6.1MB/s
Copying from local server with 250ms of RTT latency = 0.251MB/s
Copying many small files with 250ms of RTT latency = 0.64 files per second

New behavior:
Copying from local server = 13MB/s
Copying from local server with 250ms of RTT latency = 6.6MB/s
Copying many small files with 250ms of RTT latency = 1.24 files per second

OpenSSH sftp client:
Copying from local server = 14.2MB/s
Copying from local server with 250ms of RTT latency = 6.4MB/s
Copying many small files with 250ms of RTT latency = 1.34 files per second

== PUSH ==
Some benchmark figures:
Old behavior:
Copying from local server = 6.1MB/s
Copying from local server with 250ms of RTT latency = 0.249MB/s
Copying many small files with 250ms of RTT latency = 0.93 files per second

New behavior:
Copying from local server = 12.2MB/s
Copying from local server with 250ms of RTT latency = 6.2MB/s
Copying many small files with 250ms of RTT latency = 1.24 files per second

OpenSSH sftp client:
Copying from local server = 12.8MB/s
Copying from local server with 250ms of RTT latency = 6.7MB/s
Copying many small files with 250ms of RTT latency = 1.33 files per second

thanks for tracking the changes/testing/reporting issues. Does it mean your bug is a duplicate of bug #250517?

Yes, that is the same issue, this report would be the solution to that issue.

The updated patches appear to correct the hanging issue. I've updated my PPA builds with the latest patches.