MAINTAINERS: add a couple more files to the Clang/LLVM section

The K: entry should ensure that Nick and I always get CC'd on patches that
touch these files but it is better to be explicit rather than implicit.

Link: https://lkml.kernel.org/r/20210114004059.2129921-1-natechancellor@gmail.com
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: nathanchance

MAINTAINERS

@@ -4311,7 +4311,9 @@ W:	https://clangbuiltlinux.github.io/
 B:	https://github.com/ClangBuiltLinux/linux/issues
 C:	irc://chat.freenode.net/clangbuiltlinux
 F:	Documentation/kbuild/llvm.rst
+F:	include/linux/compiler-clang.h
 F:	scripts/clang-tools/
+F:	scripts/clang-version.sh
 F:	scripts/lld-version.sh
 K:	\b(?i:clang|llvm)\b