config: Print host glibc version [Linux]

[sjackman]

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[MikeMcQuaid]

When is it nil and when is it null? I'd say it'd be better to return a consistent value.

[sjackman]

It's always null?. I was being unnecessarily paranoid.

[MikeMcQuaid]

Does this need to be required globally? I wish we didn't do that for os/mac

[sjackman]

No, it doesn't. I was just following the same pattern. Fixed.

[MikeMcQuaid]

Could this just be required from system_config or even just be in that file itself if it's only used there?

[sjackman]

Yes, it can be required by system_config. Done.
This method will be used later by the bottle-pouring logic to ensure that a new enough glibc is installed to use bottles.

[MikeMcQuaid]

Cool, that's fine.

[MikeMcQuaid]

Is this method going to be used in other PRs? Otherwise can you just roll it into host_glibc_version with a return "N/A" if version.null?

[sjackman]

I've rolled maybe_na into host_glibc_version.

[MikeMcQuaid]

Cool, that's fine.

[MikeMcQuaid]

Thanks again @sjackman!

[sjackman]

Thanks for merging, Mike!