Log Message:
Update to 0.9.0

Changelog:
## 0.9.0
     * Support to generate C headers with C++ compatibility.
       https://github.com/eqrion/cbindgen/pull/349
     * Fix include guard generation when no_includes is set.
       https://github.com/eqrion/cbindgen/pull/352
     * Fix crate parsing order so that types from the binding crate
       are preferred in presence of conflicting names.
       https://github.com/eqrion/cbindgen/pull/355
     * Add extra_bindings option to generate bindings for dependencies.
       https://github.com/eqrion/cbindgen/pull/362
     * Clap dependency is optional now so it's feasible to avoid
       building it if cbindgen is used as a library.
       https://github.com/eqrion/cbindgen/pull/363