port: flesh out the input system a bit

include/PR/os_cont.h

@@ -60,6 +60,12 @@ typedef struct {
 	u16     button;
 	s8      stick_x;		/* -80 <= stick_x <= 80 */
 	s8      stick_y;		/* -80 <= stick_y <= 80 */
+#ifndef PLATFORM_N64	/* for that sick mouselook */
+	s32     mouse_x;
+	s32     mouse_y;
+	s32     mouse_dx;
+	s32     mouse_dy;
+#endif
 	u8	errnum;
 } OSContPad;