Even though flush was being done, it was ignored

- Flushing everything, even the "did anything happen" flag
meant...nothing happened
- Setting the updated flag after flushing the USB buffers fixes the
RCtrl+RShift being held issue on Kira
- Fixes Issue #308

Output/USB/output_usb.c

@@ -739,6 +739,11 @@ void USB_flushBuffers()
 	USBMouse_VertWheel = 0;
 	USBMouse_HoriWheel = 0;
 	USBMouse_Changed = 0;
+
+	// Make sure everything actually flushes
+	USBKeys_primary.changed = 1;
+	USBKeys_idle.changed = 1;
+	USBMouse_Changed = 1;
 }