update config.guess and config.sub from mainstream

build-scripts/config.guess

@@ -1,10 +1,10 @@
 #! /bin/sh
 # Attempt to guess a canonical system name.
-#   Copyright 1992-2023 Free Software Foundation, Inc.
+#   Copyright 1992-2024 Free Software Foundation, Inc.
 
 # shellcheck disable=SC2006,SC2268 # see below for rationale
 
-timestamp='2023-08-22'
+timestamp='2024-01-01'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -60,7 +60,7 @@ version="\
 GNU config.guess ($timestamp)
 
 Originally written by Per Bothner.
-Copyright 1992-2023 Free Software Foundation, Inc.
+Copyright 1992-2024 Free Software Foundation, Inc.
 
 This is free software; see the source for copying conditions.  There is NO
 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE."
@@ -165,6 +165,8 @@ Linux|GNU|GNU/*)
 	LIBC=dietlibc
 	#elif defined(__GLIBC__)
 	LIBC=gnu
+	#elif defined(__LLVM_LIBC__)
+	LIBC=llvm
 	#else
 	#include <stdarg.h>
 	/* First heuristic to detect musl libc.  */
@@ -1593,6 +1595,9 @@ EOF
     *:Unleashed:*:*)
 	GUESS=$UNAME_MACHINE-unknown-unleashed$UNAME_RELEASE
 	;;
+    *:Ironclad:*:*)
+	GUESS=$UNAME_MACHINE-unknown-ironclad
+	;;
 esac
 
 # Do we have a guess based on uname results?