Minimum bar - compile on Windows (containerd dependency)

[lowenna]

Signed-off-by: John Howard jhoward@microsoft.com

@icecrime - Minimum bar to even start looking at containerd. Containerd pulls in opencontainer\specs which does not compile on Windows. This needs merging here and vendoring into containerd to make any chance of starting forward progress.

[hqhq]

I think #310 is working on this.

[lowenna]

@hqhq Right, yes, that PR does meet the minimum bar for compiling on Windows (but I doubt it's usable in its current form on Windows). @vbatts Do you know what that PR is held up on? I'm kind of stuck making any forward progress without some fix in specs.

[lowenna]

Closing for now. Working around it in containerd in the interim pending #310

[vbatts]

thanks @jhowardmsft I'll rebase #310 and finish that work.