Add bindings for v0.18.0 and backport USDT support.

[tobz]

This PR is primarily centered around adding USDT support.

We've added bindings for v0.18.0 as I initially did so to test adding USDT support. Once that was sorted, per a comment on this PR, I went and backported USDT support all the way to v0.6.1 by generating new bindings.

Included in the PR, as well, is a simple shell script, suitable for use on Ubuntu, to make generating bindings a little more repeatable.

Closes #62

[brayniac]

Thanks for looking at this. I don't particularly object to regenerating previous versions where we can add USDT support. I don't think it would break anything that we're already exposing to do that. Adding support for 0.18.0 is definitely welcome though.

[tobz]

Yeah, I can take a stab at regenerating older bindings where USDT support was present.

(Note to self: based on cruising the Git tags for iovisor/bcc, we can likely go back as far as v0.6.0 based on the C API methods we need in rust-bpf/rust-bcc#171 for getting USDT support working.)

[tobz]

@brayniac I believe this is ready for a proper review now.

• I've added bindings for v0.18.0.
• I've backported USDT support from versions v0.6.1 and up.
• I've added a simple Ubuntu-specific script for helping generate bindings in the future.

All tests pass, and looking at the regenerated bindings by hand seems like it's mostly just clean-up from the bindgen side i.e. better handling of struct alignment and other BC changes. There's a bit of reordering of types and such that make the diffs a little gnarly to inspect. Not sure what the best way would be to better highlight actual changes vs code reordering, but maybe this doesn't matter as long as the tests pass?

[brayniac]

Thanks @tobz - yeah, for this crate I think we have to rely on the smoketest and then making sure it's all working with the bcc crate.

It looks like I've forgotten to modify the smoketest to cover 0.16.0 and 0.17.0 - see https://github.com/rust-bpf/bcc-sys/blob/master/examples/smoketest.rs#L33 - it passed when I merged both of those, but now that they're not the latest versions... we're technically not testing that they didn't obviously break with this PR. If you don't mind fixing that up so we have proper test coverage for this PR that would be great.

Otherwise this looks good. Thanks for spending time on the USDT support!

[tobz]

Alright. smoke test adjusted, and things still look good.

[brayniac]

v0.18.0 is published to crates.io

Thanks again!