Build different binaries for different libc’s (a.k.a. support alpine linux)

[bkw]

The latest version of node-pre-gyp supports using libc as a variable for binary names, making it possible to differentiate between glibc and musl of alpine linux.

Fixes #81.

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[bkw]

CLA signed.

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CLAs look good, thanks!

[murgatroid99]

Can you make the corresponding change to packages/grpc-native-core/templates/package.json.template?

[bkw]

Thanks for spotting that. Done in 4479312.

[bkw]

I think it would make a lot of sense to have a precompiled musl build to save on build dependencies.
Is there any place I could add an alpine build to the release pipeline? I can't seem to find where the precompiled binaries are actually being build or uploaded. Is that a kokoro thing, perhaps?

[bkw]

Is there anything else I can do to push this forward?

[loganbfisher]

Is there any way this can get merged? We are running into this problem with a number of our images currently. Thanks for the fix!

[victorperin]

Same here, delaying deploys of some features too. :)

[BrunoQuaresma]

Any prediction of launch new version?