add buildkitd.exe to windows binaries

[iankingori]

No description provided.

[profnandaa]

nit: do we remove line 324 (FROM...) too then?

[iankingori]

We aren't doing anything to the image for now but it is used here when TARGETOS is windows

[crazy-max]

I don't think we want to release buildkitd for windows yet as this is not stable. We only produce it in the Dockerfile for testing:

buildkit/Dockerfile

Line 325 in 4b95d74

# this is not in binaries-windows because it is not intended for release yet, just CI

See also #616

[tonistiigi]

@crazy-max What's the issue? We can mark it experimental in the release changelog.

[tonistiigi]

@iankingori Ideally this should work with the OCI worker as well in the release. I think atm it only works with containerd worker. With OCI worker the release tarball should contain all required extra assets (eg. linux version contains runc). We also need some documentaion that would guide users through the setup and simple usage flow, especially if setting up containerd would still be required in v0.13.

[iankingori]

Thanks for merging @crazy-max.

@tonistiigi we are currently working on the OCI worker and shall update the docs with a windows how to guide.