Allow the libusb20_dev_get_port_path() function to be called when the
USB device is closed. This fixes a compatibility issue with upstream
libusb.

Found by:	romain@

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from:	pfg

Some libusb consumers in Linux-land (in this case, libusb4java) expect a
dev_capability member that they can use to enumerate the device
capabilities.

No particular layout is expected of this, just that it can be traversed
using the bLength member until bNumDeviceCapabilities are read and that the
consumer may then use one of the libusb_get_*_descriptor methods to extract
specific (usb 2.0 vs. ss) capability information.

Fix libusb20_dev_get_desc(3) to use the "vendor product" order, not
"product vendor". This is consistent with how it's generally done.

The ordering is visible eg in usbconfig(8) output.

Fix array size issue when using the pre-scaling feature for
ISOCHRONOUS USB transfers. Make sure enough length and buffer pointers
are allocated when setting up the libusb transfer structure to support
the maximum number of frames the kernel can handle.

Approved by:	re (marius)
PR:		210509
MFC after:	1 week

libusb(3) manual page.

Approved by:	re (gjb)
Requested by:	swills
MFC after:	1 week

libusb_hotplug_deregister_callback() for the LibUSB v1.0 API and
update the libusb(3) manual page.

Approved by:	re (kib)
Requested by:	swills
MFC after:	1 week

Approved by:	re (gjb)
MFC after:	1 week