Allow statically linking libclang

[jsgf]

The bindgen Cargo.toml mentions a "static" feature, but it doesn't seem to connect to anything. Its dependency on clang-sys always sets the "runtime" features, which forces runtime dynamic loading.

I'd like to build bindgen statically linked with libclang, mostly to make deployment easier. It would be nice to be able to pass the "static" feature through to clang-sys rather than always requiring "runtime".

[emilio]

Wow, looks like that feature has survived all the way since d54fe74 (when it did what it claimed!).

I didn't check what broke it, but probably the switch to libclang clang-sys.

[emilio]

So, I think this is fair. Though right now we support runtime checks for a lot of stuff (so if a libclang function is not available, we fall back, and such).

Would it be acceptable to require a new-enough version of libclang? i.e., something like 6.0 or such?

If so, it should be feasible to build this and conditionally compiling the is_loaded checks for example...

[jsgf]

I have a PR in progress.

[emilio]

Sweet! :)

[emilio]

Fixed by #1620 and #1649.

[jethrogb]

This is the cause of #2030