IsDeviceUsable in IOhidapi.cpp uses errno to detect if hid_write failed because of an unconnected Wiimote on a Dolphinbar (it expects errno == EPIPE in this case).
macOS’s implementation of hid_write detected this specific error (IOHIDDeviceSetReport returns kUSBHostReturnPipeStalled) but didn’t set errno so the check failed.
This add errno assignment to failure cases of macOS’s hid_write.
If available, use the system-generated unique ID for HID device paths instead of a transport/vid/pid/location tuple.
The Mayflash Dolphinbar registers four HID devices (regardless of the number of connected Wiimotes) which had the same path with the previous path building method, causing a bit of confusion when detecting and connecting to Wiimotes.
The unique IDs do not change if the computer is suspended and resumed, but do change if the HID device is unplugged/replugged.
