Take libakerror 2.0.2, libakstdlib and libakgl 0.9.0

Bumps all three ak* submodules to their current main, applies what their
upgrade notes require, and retires the two workarounds they make obsolete.

libakerror 2.0.1 -> 2.0.2 (63 commits). Two of its fixes were this
repository's own filed issues, and both workarounds are gone:

  - It namespaces its embedded `coverage` target now, the same
    CMAKE_SOURCE_DIR test it already applied to `mutation` (its issue #15).
    The add_custom_target() shadow that renamed it on the way past could
    only ever fire on a name the dependency has stopped using, so it is
    deleted rather than left as dead code.
  - It installs akerrorConfigVersion.cmake at SameMajorVersion (its issue
    #16). MAINTENANCE.md said to add a `1.0` floor to our find_dependency
    calls when this landed; the floor is now `2.0`, and we have no
    find_dependency calls to add it to, so the paragraph says that instead
    of an instruction nobody can follow.

Its IGNORE context also changed shape: `__akerr_last_ignored` was an extern
pointer, and is now a per-translation-unit `static akerr_last_ignored` holding
a copy, so the pool slot can be released. Nothing here referenced the symbol,
but it costs us 1.35 MiB of thread-local storage -- 38 TUs x 37,296 bytes,
measured as the entire TLS segment of build/basic, where 2.0.1 produced no TLS
segment at all -- plus 84 -Wunused-variable warnings. Filed upstream as
libakerror issue #37 and recorded in MAINTENANCE.md rather than patched here,
because patching a submodule forks it.

libakstdlib gains directory and file-metadata wrappers with no version bump.
aksl_snprintf keeps its `int *count` -- an intermediate commit removed it and
the merge put it back -- but now reports the required length on truncation
rather than 0. Every call site here reads it only after a successful return,
so nothing moved.

The directory wrappers close the gap DIRECTORY was refused for (libakstdlib
issue #10). The verb is still unwritten, so it still refuses, but it no longer
blames a wrapper that exists: the message is "DIRECTORY is not implemented
yet" and tests/disk_verbs.c asserts both that it says so and that it does not
name libakstdlib. What writing it would need is akbasic issue #55.

libakgl moves to the current main at 0.9.0. It registers libccd and tg as
submodules, so a tree that only ran `git submodule update --init --recursive`
before the bump needs it again or the configure fails on a missing
libccd/src/ccd/config.h.cmake.in.

Verified: 114/114 default, 116/116 under -DAKBASIC_WITH_AKGL=ON, docs_examples
green in both. libakerror's UPGRADING.md documents a 2.0.3 that project()
never stamped, so the version tables read 2.0.2 -- libakerror issue #38.

Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
Co-Authored-By: Claude Code (Claude Opus 5, claude-opus-5[1m]) <noreply@anthropic.com>

CMakeLists.txt

@@ -51,12 +51,14 @@ option(AKBASIC_SANITIZE  "Build with ASan + UBSan"                           OFF
 # through: the dependencies set target and directory properties that their own
 # builds depend on.
 #
-# libakerror additionally namespaces its `mutation` target when embedded but not
-# its `coverage` target (deps/libakerror/CMakeLists.txt:194 vs :172), so a
-# coverage build collides on the `coverage` target and fails to configure at all.
-# Rename the dependency's on the way past. Remove this once libakerror applies
-# the same CMAKE_SOURCE_DIR test to `coverage` that it already applies to
-# `mutation` -- filed as libakerror issue #15.
+# All three dependencies now namespace both their `coverage` and their
+# `mutation` targets when embedded, so there is no custom-target collision left
+# to work around. libakerror was the last holdout -- it namespaced `mutation`
+# but not `coverage`, and a coverage build collided on the bare name and failed
+# to configure at all. 2.0.2 applies the same CMAKE_SOURCE_DIR test to both
+# (deps/libakerror/CMakeLists.txt:429-434), closing libakerror issue #15, and
+# the add_custom_target() shadow that renamed it on the way past is gone with
+# this comment.
 #
 # **Only one project in a tree may shadow add_test(), and this is that project.**
 # CMake exposes an overridden command as `_name` and chains exactly one level: a
@@ -86,14 +88,6 @@ function(set_property _scope)
   endif()
 endfunction()
 
-function(add_custom_target _name)
-  if(AKBASIC_SUPPRESS_ADD_TEST AND _name STREQUAL "coverage")
-    _add_custom_target(akerror_coverage ${ARGN})
-  else()
-    _add_custom_target(${ARGV})
-  endif()
-endfunction()
-
 add_subdirectory(deps/libakerror EXCLUDE_FROM_ALL)
 add_subdirectory(deps/libakstdlib EXCLUDE_FROM_ALL)
 if(AKBASIC_WITH_AKGL)