MFC r261123:
Reduce dmesg verbosity.
MFC r261004, r261005 and r261033:
Adjust the DMA delay logic so that the DMA delay does not become too small.
MFC r261224:
Comply to the official LibUSB v1.0 API:
"It is legal to attempt to claim an already-claimed interface."
MFC r261228:
When detaching a [USB] keyboard, keys might still be pressed. Ensure
that all pressed keys are released before completing the USB keyboard
detach. This will prevent so-called "ghost-keys" from appearing after
that the USB device generating the key event(s) has been detached.
MFC r260315:
Implement two new libusb API functions.

PR:		usb/185454
MFC: r233049 by rmh

Remove gratuitous DEBUG_FLAGS="-g" setting (this is already the default
option with GENERIC kernels).

PR:		179536
Submitted by:	Alexey Markov
MFC r244535, r245995, r261505 and r258961:
- Use a boundary of zero, hence a PAGE_SIZE boundary
is implied by all memory allocations.
- Fix an external compiler warning about write-only
assigned variable.