Static functions don't work

[adetaylor]

#[test]
fn test_static_function() {
    let cxx = indoc! {"
        Bob Bob::create() { Bob a; return a; }
    "};
    let hdr = indoc! {"
        #include <cstdint>
        struct Bob {
            uint32_t a;
            static Bob create();
        };
    "};
    let rs = quote! {
        ffi::Bob::create();
    };
    run_test(cxx, hdr, rs, &[], &["Bob"]);
}

We are not turning create into an associated function as we should.

[adetaylor]

Duplicate of #89, silly me.