Function ZL_ReflectionCtx_getDCtx 

pub unsafe extern "C" fn ZL_ReflectionCtx_getDCtx(
    rctx: *mut ZL_ReflectionCtx,
) -> *mut ZL_DCtx

@returns The dctx that will be used for decompression so the user can set parameters and register custom transforms if the helpers provided aren’t sufficient.

@pre Must be called before ZL_ReflectionCtx_setCompressedFrame().