check-engines needs to ignore odd numbered nodejs versions.

[wraithgar]

odd numbered node.js versions are already not "supported" and are a problem when other packages adjust their engines entries to start omitting them.

node.js versions are not 100% semver, the odd numbered versions are immediately "dropped" when the next even number is released.

This is not a trivial change, but we should find a way to check the parts of an engines declaration that don't overlap are odd numbers (for node) and ignore that.