MAINTAINERS: refresh LLVM support

MAINTAINERS: refresh LLVM support

As discussed at the ClangBuiltLinux '23 meetup (co-located with Linux Plumbers
Conf '23), I'll be taking a step back from kernel work to focus on my growing
family and helping Google figure out its libc story. So I think it's time to
formally hand over the reigns to my co-maintainer Nathan.

As such, remove myself from reviewer for:
- CLANG CONTROL FLOW INTEGRITY SUPPORT
- COMPILER ATTRIBUTES
- KERNEL BUILD

For CLANG/LLVM BUILD SUPPORT I'm bumping myself down from maintainer to
reviewer, adding Bill and Justin, and removing Tom (Tom and I confirmed this
via private email; thanks for the work done Tom, ++beers_owed).

It has been my pleasure to work with everyone to improve the toolchain
portability of the Linux kernel, and to help bring LLVM to the table as a
competitor. The work here is not done.  I have a few last LLVM patches in the
works to improve stack usage of clang which has been our longest standing open
issue (getting "rm" inline asm constraints to DTRT is part of that). But
looking back I'm incredibly proud of where we are to today relative to where we
were when we started the ClangBuiltLinux journey, and am confident that the
team and processes we have put in place will continue to be successful. I
continue to believe that a rising tide will lift all boats.

I identify first and foremost as a Linux kernel developer, and an LLVM dev
second. May it be a cold day in hell when that changes.

Wake me when you need me.

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Bill Wendling <morbo@google.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20231117-maintainers-v1-1-85f2a7422ed9@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>