Redirect boringssl submodule url to open-quantum-safe fork

[kevinmkane]

Commit 2faa797 updated the boringssl submodule to a commit that only exists in the open-quantum-safe/boringssl fork, but the .gitmodules file still references the official BoringSSL repo. This causes git submodule update or git clone --recurse-submodules to now fail. This change clones the submodule from OQS's fork instead, where the commit exists.

[dstebila]

Hi Kevin! I also ran into some gitsubmodule weirdness when I was working with the OpenSSL repo earlier today but assumed it was just a misconfiguration on my side. But perhaps not. However I'm not sure we need to actually point to a commit OQS-BoringSSL, as I didn't think OQS-OpenSSL doesn't have OQS-BoringSSL as a dependency. @xvzcf how do you want to proceed?

[xvzcf]

Updating the commit in that PR was a mistake, I was using the submodule to locally test interoperability and did not intend to commit the change.

That being said, it might be a good idea to keep it and point the submodule URL to our fork. Even if we move the interoperability tests out of this repository, OpenSSL provides the ability to run the BoringSSL tests against OpenSSL; while I have not tried this test suite yet, I do intend to look into it since it might be worthwhile to ensure that it works with our fork of BoringSSL (rather than the mainline project).