Network overhaul : support for multiple NICs, performance improvement

- Add support for multiple NICs
- Switch from polling to an event loop for the host networking to avoid latency and locking issues

src/include/86box/net_event.h

@@ -0,0 +1,22 @@
+#ifndef EMU_NET_EVENT_H
+#define EMU_NET_EVENT_H
+
+typedef struct {
+#ifdef _WIN32
+    HANDLE handle;
+#else
+    int fds[2];
+#endif
+} net_evt_t;
+
+extern void net_event_init(net_evt_t *event);
+extern void net_event_set(net_evt_t *event);
+extern void net_event_clear(net_evt_t *event);
+extern void net_event_close(net_evt_t *event);
+#ifdef _WIN32
+extern HANDLE net_event_get_handle(net_evt_t *event);
+#else
+extern int net_event_get_fd(net_evt_t *event);
+#endif
+
+#endif