Re: [PATCH v5 3/4] rust: add a Kconfig function to test for support of bindgen options

[Asuna Yang]

> The -x argument should explicitly tell (lib)clang what language the file
> is without needing an extension. I don't know why it's not working for
> you...

Didn't realize that I should pass a `-x` to the backend. It works now, 
I'll include it in the next revision. Thanks.