Git: Upgrade to Cygwin v2.11.1

[dscho]

It was just released: https://github.com/cygwin/cygwin/releases/tag/cygwin-2_11_0-release (although there is no announcement on the Cygwin mailing list yet, but there is some information about the fourth test release).

Now, it is way too close to Git for Windows v2.19.0, with already three pre-releases having been tested, and I do not want to risk anything by upgrading our MSYS2 runtime in the meantime.

Looking through the bug fixes, it seems that the only relevant one is the fix for https://cygwin.com/ml/cygwin/2018-05//msg00017.html, where path translation sometimes resulted in buffer under-runs.

We already backported https://cygwin.com/ml/cygwin-patches/2018-q2/msg00016.html.

Of the remaining bug fixes, I could imagine that https://cygwin.com/ml/cygwin/2018-08/msg00295.html might bite the occasional Git for Windows user, but I have not heard anything in that direction yet.

My current plan, therefore, is to hold off with updating our MSYS2 runtime fork to Cygwin v2.11.0 until after Git for Windows v2.19.0 will be released, on or around September 10th 2018.

[dscho]

Cc @jamill

[dscho]

Update: Cygwin v2.11.1 was released in the meantime.

[dscho]

And I upgraded to Cygwin v2.11.2, after all.