Update CHERI libc++ to LLVM17

Sync the libc++ build files with upstream LLVM 17 (commit
8a4dda3).

This commit also includes the subrepo update since otherwise we would
end up with a non-buildable commit.

ObsoleteFiles.inc

@@ -1014,8 +1014,6 @@ OLD_DIRS+=usr/lib/clang/16/share
 OLD_DIRS+=usr/lib/clang/16
 
 # 20231208: new libc++ import which bumps version from 16 to 17
-.if 0
-# CHERI libc++ is still from 15.0.0
 OLD_FILES+=usr/include/c++/v1/__bsd_locale_defaults.h
 OLD_FILES+=usr/include/c++/v1/__bsd_locale_fallbacks.h
 OLD_FILES+=usr/include/c++/v1/__debug
@@ -1038,7 +1036,6 @@ OLD_DIRS+=usr/include/c++/v1/__tuple_dir
 OLD_FILES+=usr/include/c++/v1/experimental/algorithm
 OLD_FILES+=usr/include/c++/v1/experimental/coroutine
 OLD_FILES+=usr/include/c++/v1/experimental/functional
-.endif
 
 # 20231117: libufs version bumped to 8
 OLD_LIBS+=lib/libufs.so.7
@@ -1551,12 +1548,9 @@ OLD_DIRS+=usr/lib/clang/15.0.7/share
 OLD_DIRS+=usr/lib/clang/15.0.7
 
 # 20230622: new libc++ import which bumps version from 15.0.7 to 16.0.1
-.if 0
-# CHERI libc++ is still from 15.0.0
 OLD_FILES+=usr/include/c++/v1/__bits
 OLD_FILES+=usr/include/c++/v1/__tuple
 OLD_FILES+=usr/include/c++/v1/__utility/transaction.h
-.endif
 
 # 20230614: caroot bundle updated
 OLD_FILES+=usr/share/certs/trusted/Cybertrust_Global_Root.pem

etc/mtree/BSD.debug.dist

@@ -30,7 +30,7 @@
                 c18n
                 ..
                 clang
-                    18
+                    17
                         lib
                             freebsd
                             ..

etc/mtree/BSD.include.dist

@@ -17,6 +17,12 @@
     c++
         v1
             __algorithm
+                pstl_backends
+                    cpu_backends
+                    ..
+                ..
+            ..
+            __atomic
             ..
             __bit
             ..
@@ -28,10 +34,14 @@
             ..
             __concepts
             ..
+            __condition_variable
+            ..
             __coroutine
             ..
             __debug_utils
             ..
+            __exception
+            ..
             __expected
             ..
             __filesystem
@@ -46,21 +56,39 @@
             ..
             __iterator
             ..
+            __locale_dir
+                locale_base_api
+                ..
+            ..
+            __mdspan
+            ..
             __memory
             ..
             __memory_resource
             ..
+            __mutex
+            ..
             __numeric
             ..
+            __pstl
+                internal
+                    omp
+                    ..
+                ..
+            ..
             __random
             ..
             __ranges
             ..
+            __stop_token
+            ..
             __string
             ..
+            __system_error
+            ..
             __thread
             ..
-            __tuple_dir
+            __tuple
             ..
             __type_traits
             ..
@@ -69,8 +97,6 @@
             __variant
             ..
             experimental
-                __simd
-                ..
             ..
             ext
             ..

etc/mtree/BSD.usr.dist

@@ -36,7 +36,7 @@
     ..
     lib
         clang
-            18
+            17
                 include
                     cuda_wrappers
                         bits