Function poppler_sys::poppler_document_sign

pub unsafe extern "C" fn poppler_document_sign(
    document: *mut PopplerDocument,
    signing_data: *const PopplerSigningData,
    cancellable: *mut GCancellable,
    callback: GAsyncReadyCallback,
    user_data: gpointer,
)

Available on crate feature v23_7 only.