/// Declares the `vlog_startup_routines` symbol required by VPI simulators.
///
/// Provide one or more `extern "C" fn()` routine names. The macro emits a
/// null-terminated function pointer table as expected by common simulators.
///
/// # Example
/// ```ignore
/// extern "C" fn register() {
/// // Register callbacks/system tasks.
/// }
///
/// vpi::startup_routines!(register);
/// ```
/// Counts macro expression arguments at compile time.
///
/// This is primarily used internally by [`startup_routines!`].