Add an option to not generate "methods" when dynamic linking

[Srlion]

I think the code part for this is in here: https://github.com/rust-lang/rust-bindgen/blob/50ec3ee0d9436ff0d6e50c5ff59bf05ef137b386/bindgen/codegen/dyngen.rs#L176

where would it be possible to just have like .dynamic_no_methods(true)

[emilio]

Doesn't the existing blocklisting / allowlisting methods allow you enough control over this?