The 82C606 SuperIO allows reconfiguring the interrupt line used for the
UART alarm at runtime, including disabling it altogether.
While at that, correct the type in the serial_setup() prototype to be
the same as serial_t.irq uses.
- 86Box's own headers go to /86box
- munt's public interface goes to /mt32emu
- all slirp headers go to /slirp (might want to consider using only its public inteface)
- single file headers from other projects go in include root
