[Windows] Freeze PKG_VERSION and add fallback lookup in default installation path

[jaimergp]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

Part 1

This fixes a subtle bug I just found for the activation scripts on Windows. Since we are not creating the activation scripts from the install script, but by copying them from files, environment variables are not rendered to the final file. Instead the take the value set in the environment when they are executed. For our tests that didn't matter because they got rendered correctly, but when used in other recipes, they might take the wrong value.

For example, the CUDA version check uses PKG_VERSION, which will be set for other packages during build time. Example here. That 7.5.0 is OpenMM's version, not CUDA!

To fix this, I am rendering PKG_VERSION by hand, using sed 😬

This is not producing errors because of the fallback mechanisms for finding CUDA_HOME, but that doesn't mean it should not be fixed. Especially if this package is used outside the context of conda-forge.

Part 2

For some reason, in some feedstocks conda-forge-ci-setup mechanisms do not reach the recipe (e.g. CUDA_PATH is not set and PATH does not contain nvcc.exe). See #53 for more details.

As a workaround I am adding a fallback lookup in the default installation path, where the activation script might find nvcc.exe.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[jaimergp]

@conda-forge/nvcc I think this is ready for review. If you agree, I'd like to add me as a maintainer for the Windows bits too.

[kkraus14]

@conda-forge/nvcc I think this is ready for review. If you agree, I'd like to add me as a maintainer for the Windows bits too.

Sounds good to me, please add yourself as a maintainer on the recipe!

[kkraus14]

One typo, but approach LGTM

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I was trying to look for recipes to lint for you, but it appears we have a merge conflict.
Please try to merge or rebase with the base branch to resolve this conflict.

Please ping the 'conda-forge/core' team (using the @ notation in a comment) if you believe this is a bug.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[jaimergp]

Thanks!