Add support for static linking

[palfrey]

Enable support for static linking with the feature flag static. This aids the building of single binaries with no system dependencies on systems that support static linking with Rust (e.g. particularly alpine, but theoretically others).

[pacman82]

Hi, thanks for your contribution! Can you make the tests pass, and give me a short tl;dr of what you did?

[palfrey]

Hi, thanks for your contribution! Can you make the tests pass, and give me a short tl;dr of what you did?

I've just updated the description with the tl;dr of what it is, and I'll be adding some comments to specific items on why they're there as some of them are non-obvious. On the tests passing:

• Ubuntu: now working with the bionic update, as the xenial version of unixodbc didn't properly support static linking.
• OS X: currently blocked on an upstream issue in Homebrew that I'm working on getting fixed found how to deal with.
• Windows: I think the problem is that the path to the library is wrong, but I need to boot back up my test Windows system and see if I can have another shot at that. The Appveyor information on what's installed where is a little sparse, and so I'm having to attempt to reconstruct bits of it, add a path and see if it suceeds. I've disabled static linking entirely for the Windows build, as I'm not convinced it's doable. OTOH, odbc is part of the Windows core libraries as best I can tell, so it shouldn't be an obstacle to making portable binaries.

[palfrey]

Workaround for https://travis-ci.community/t/syntax-error-unexpected-keyword-rescue-expecting-keyword-end-in-homebrew/5623

[pacman82]

That would make a great comment for the travis file itself.

[palfrey]

Done

[palfrey]

Xenial had an older version of unixodbc that didn't support static linking properly.

[pacman82]

Great work!

[pacman82]

That would make a great comment for the travis file itself.