Externals: Update libusb to 1.0.23-rc1

Now has support for isochronous transfers in the WinUSB backend,
which may or may not work better than the UsbDk backend.

Externals/libusb/AUTHORS

@@ -8,14 +8,19 @@ Copyright © 2010-2012 Michael Plante <michael.plante@gmail.com>
 Copyright © 2011-2013 Hans de Goede <hdegoede@redhat.com>
 Copyright © 2012-2013 Martin Pieuchot <mpi@openbsd.org>
 Copyright © 2012-2013 Toby Gray <toby.gray@realvnc.com>
-Copyright © 2013-2015 Chris Dickens <christopher.a.dickens@gmail.com>
+Copyright © 2013-2018 Chris Dickens <christopher.a.dickens@gmail.com>
 
 Other contributors:
+Adrian Bunk
 Akshay Jaggi
 Alan Ott
 Alan Stern
 Alex Vatchenko
 Andrew Fernandes
+Andy Chunyu
+Andy McFadden
+Angus Gratton
+Anil Nair
 Anthony Clay
 Antonio Ospite
 Artem Egorkine
@@ -23,12 +28,17 @@ Aurelien Jarno
 Bastien Nocera
 Bei Zhang
 Benjamin Dobell
+Brent Rector
 Carl Karsten
+Christophe Zeitouny
 Colin Walters
 Dave Camarillo
 David Engraf
 David Moore
 Davidlohr Bueso
+Dmitry Fleytman
+Doug Johnston
+Evan Hunter
 Federico Manzan
 Felipe Balbi
 Florian Albrechtskirchinger
@@ -41,23 +51,34 @@ Hans Ulrich Niedermann
 Hector Martin
 Hoi-Ho Chan
 Ilya Konstantinov
+Jakub Klama
 James Hanko
+Jeffrey Nichols
+Johann Richard
 John Sheu
+Jonathon Jongsma
+Joost Muller
+Josh Gao
 Joshua Blake
 Justin Bischoff
+KIMURA Masaru
 Karsten Koenig
 Konrad Rzepecki
 Kuangye Guo
 Lars Kanis
 Lars Wirzenius
+Lei Chen
 Luca Longinotti
 Marcus Meissner
 Markus Heidelberg
 Martin Ettl
 Martin Koegler
+Matthew Stapleton
 Matthias Bolte
+Michel Zou
 Mike Frysinger
 Mikhail Gusarov
+Morgan Leborgne
 Moritz Fischer
 Ларионов Даниил
 Nicholas Corgan
@@ -66,10 +87,17 @@ Orin Eman
 Paul Fertser
 Pekka Nikander
 Rob Walker
+Romain Vimont
+Roman Kalashnikov
+Sameeh Jubran
 Sean McBride
 Sebastian Pipping
+Sergey Serb
 Simon Haggett
 Simon Newton
+Stefan Agner
+Stefan Tauner
+Steinar H. Gunderson
 Thomas Röfer
 Tim Hutt
 Tim Roberts
@@ -81,9 +109,11 @@ Uri Lublin
 Vasily Khoruzhick
 Vegard Storheil Eriksen
 Venkatesh Shukla
+Vianney le Clément de Saint-Marcq
+Victor Toso
 Vitali Lovich
+William Skellenger
 Xiaofan Chen
 Zoltán Kovács
 Роман Донченко
 parafin
-xantares