libusb: implement libusb_hotplug_get_user_data

[aokblast]

Summary

libusb provides a function to get the callback userdata for a given
callback sincwe this structure is opaque to libusb user.

[markj]

lib/libusb/libusb.3

780

781

lib/libusb/libusb10_hotplug.c

429

Presumably you need to release the lock before returning?

Or, just break; here, and return (handle) below. It is guaranteed that TAILQ_FOREACH will set the iterator variable to NULL after the loop reaches the end of the queue and terminates.

[ziaee]

lib/libusb/libusb.3

780

returns?

[markj]

lib/libusb/libusb.3

780

Yes, sorry.

[adrian]

hi! please address the concerns in the diff (including that lock handling, heh) and then i'll approve! thanks!

[aokblast]

Minor updates

[markj]

lib/libusb/libusb10_hotplug.c

433

Don't you want to return handle here?

[aokblast]

Fix false return after drunk too much

[markj]

Approved

[lwhsu]

lib/libusb/libusb.h

597

don't forget to align the style with other functions.