MFC r338616:

MFC r338616:
Fix issues about cancelling USB transfers in LibUSB when the USB device has
been detached. When a USB device has been detached the kernel file handle
stops responding to commands. USB applications which continue to run after
the USB device has been detached, depend on LibUSB generated events to tear
down its pending USB transfers. Add code to handle the needed cleanup when
processing the USB transfer(s) fails and prevent new USB transfer(s) from
being submitted.

Found by:		Ludovic Rousseau <ludovic.rousseau+freebsd@gmail.com>
PR:			231076
Sponsored by:		Mellanox Technologies

git-svn-id: svn://svn.freebsd.org/base/stable/9@338790 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f