Install libsecp256k1 on Windows

[amesgen]

Closes #3678, alternative to #3683

This installs the prebuilt libsecp256k1 DLL built via input-output-hk/haskell.nix#1424.

[hamishmack]

I think we might also want the extra echo commands from libsodium install step and the sed to convert to windows path before adding to GITHUB_PATH.

        export PKG_CONFIG_PATH="$PKG_CONFIG_PATH;$(readlink -f secp256k1/lib/pkgconfig)"
        echo "PKG_CONFIG_PATH=$PKG_CONFIG_PATH"
        echo "PKG_CONFIG_PATH=$PKG_CONFIG_PATH" >> $GITHUB_ENV
        export SECP256K1_PATH="$(readlink -f secp256k1/bin | sed 's|^/d|D:|g' | tr / '\\')"
        echo "SECP256K1_PATH=$SECP256K1_PATH"
        echo "$SECP256K1_PATH" >> $GITHUB_PATH

[hamishmack]

I tried using temp dir for libsecp256k1 like libsodium does and that did not seem to help. I put -v3 on cabal and it did not really reveal much (but it did look like pkg-config was running and not finding the library at all).

Then I tried making the paths in PKG_CONFIG_PATH into windows paths and that seems to have fixed the issue!

It's not finished building and running the tests yet, but here is a PR to update this PR #3693.

[coot]

LGTM, thanks a bunch for the fix!

[coot]

bors merge

[iohk-bors]

This PR was included in a batch that successfully built, but then failed to merge into master. It will not be retried.

Additional information:

{"message":"2 of 4 required status checks are in progress.","documentation_url":"https://docs.github.com/articles/about-protected-branches"}

[amesgen]

I raised this error on slack.

[amesgen]

bors r+

[iohk-bors]

Build succeeded:

• build (8.10.7, ubuntu-20.04)
• build (8.10.7, windows-latest)
• ci/hydra:Cardano:ouroboros-network:required