Rust introduction for v6.1-rc1

The initial support of Rust-for-Linux comes in roughly 4 areas:

- Kernel internals (kallsyms expansion for Rust symbols, %pA format)

- Kbuild infrastructure (Rust build rules and support scripts)

- Rust crates and bindings for initial minimum viable build

- Rust kernel documentation and samples

Rust support has been in linux-next for a year and a half now, and the
short log doesn't do justice to the number of people who have contributed
both to the Linux kernel side but also to the upstream Rust side to
support the kernel's needs. Thanks to these 173 people, and many more,
who have been involved in all kinds of ways:

Miguel Ojeda, Wedson Almeida Filho, Alex Gaynor, Boqun Feng, Gary Guo,
Björn Roy Baron, Andreas Hindborg, Adam Bratschi-Kaye, Benno Lossin,
Maciej Falkowski, Finn Behrens, Sven Van Asbroeck, Asahi Lina, FUJITA
Tomonori, John Baublitz, Wei Liu, Geoffrey Thomas, Philip Herron,
Arthur Cohen, David Faust, Antoni Boucher, Philip Li, Yujie Liu,
Jonathan Corbet, Greg Kroah-Hartman, Paul E. McKenney, Josh Triplett,
Kent Overstreet, David Gow, Alice Ryhl, Robin Randhawa, Kees Cook,
Nick Desaulniers, Matthew Wilcox, Linus Walleij, Joe Perches, Michael
Ellerman, Petr Mladek, Masahiro Yamada, Arnaldo Carvalho de Melo,
Andrii Nakryiko, Konstantin Shelekhin, Rasmus Villemoes, Konstantin
Ryabitsev, Stephen Rothwell, Andy Shevchenko, Sergey Senozhatsky, John
Paul Adrian Glaubitz, David Laight, Nathan Chancellor, Jonathan
Cameron, Daniel Latypov, Shuah Khan, Brendan Higgins, Julia Lawall,
Laurent Pinchart, Geert Uytterhoeven, Akira Yokosawa, Pavel Machek,
David S. Miller, John Hawley, James Bottomley, Arnd Bergmann,
Christian Brauner, Dan Robertson, Nicholas Piggin, Zhouyi Zhou, Elena
Zannoni, Jose E. Marchesi, Leon Romanovsky, Will Deacon, Richard
Weinberger, Randy Dunlap, Paolo Bonzini, Roland Dreier, Mark Brown,
Sasha Levin, Ted Ts'o, Steven Rostedt, Jarkko Sakkinen, Michal
Kubecek, Marco Elver, Al Viro, Keith Busch, Johannes Berg, Jan Kara,
David Sterba, Connor Kuehl, Andy Lutomirski, Andrew Lunn, Alexandre
Belloni, Peter Zijlstra, Russell King, Eric W. Biederman, Willy
Tarreau, Christoph Hellwig, Emilio Cobos Álvarez, Christian Poveda,
Mark Rousskov, John Ericson, TennyZhuang, Xuanwo, Daniel Paoliello,
Manish Goregaokar, comex, Josh Stone, Stephan Sokolow, Philipp Krones,
Guillaume Gomez, Joshua Nelson, Mats Larsen, Marc Poulhiès, Samantha
Miller, Esteban Blanc, Martin Schmidt, Martin Rodriguez Reboredo,
Daniel Xu, Viresh Kumar, Bartosz Golaszewski, Vegard Nossum, Milan
Landaverde, Dariusz Sosnowski, Yuki Okushi, Matthew Bakhtiari, Wu
XiangCheng, Tiago Lam, Boris-Chengbiao Zhou, Sumera Priyadarsini,
Viktor Garske, Niklas Mohrin, Nándor István Krácser, Morgan Bartlett,
Miguel Cano, Léo Lanteri Thauvin, Julian Merkle, Andreas Reindl,
Jiapeng Chong, Fox Chen, Douglas Su, Antonio Terceiro, SeongJae Park,
Sergio González Collado, Ngo Iok Ui (Wu Yu Wei), Joshua Abraham,
Milan, Daniel Kolsoi, ahomescu, Manas, Luis Gerhorst, Li Hongyu,
Philipp Gesang, Russell Currey, Jalil David Salamé Messina, Jon Olson,
Raghvender, Angelos, Kaviraj Kanagaraj, Paul Römer, Sladyn Nunes,
Mauro Baladés, Hsiang-Cheng Yang, Abhik Jain, Hongyu Li, Sean Nash,
Yuheng Su, Peng Hao, Anhad Singh, Roel Kluin, Sara Saa, Geert
Stappers, Garrett LeSage, IFo Hancroft, and Linus Torvalds.
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