LATX, fix: Release AOT merge and invalidated segment resources

[LaurenIsACoder]

Scope

Based on current upstream 525b456fb5fc. Fix AOT resources whose owning operation has finished:

• Free both merge-input buffers and their vector on success, duplicate input, and errors.
• Destroy non-TU merge indexes before their borrowed input data is freed; free owned TB-index values on replacement and destruction.
• Free directory-scan allocations when opening the cache directory fails.
• Invalidate every overlapping segment on successful unmap, remap, or replacement, instead of only the first match. Segment-owned address-specific PE/cache mappings are released; reusable ELF library-cache entries retain their existing policy.

This does not duplicate upstream's AOT reader fix (17b479de7877) or change the cache format or capacity. Thread ownership changes in #472 remain separate.

Validation

Validated on LoongArch64 with GCC 14.2.0. Both configurations used LAT O1, AOT, release settings, enabled tests, and at most two build or test processes.

../configure --target-list=x86_64-linux-user --enable-latx \
  --enable-latx-aot --optimize-O1 --extra-ldflags=-ldl --enable-kzt \
  --enable-tests --disable-debug-info --disable-docs --disable-werror \
  --meson=meson
ninja -j2 all meson-test-prereq
env -u LAT_LD_PREFIX meson test --suite lat-pr-fast --no-rebuild \
  --num-processes 2 --print-errorlogs

../configure --target-list=i386-linux-user --enable-latx \
  --enable-latx-aot --enable-guest-base-zero --optimize-O1 \
  --enable-tests --disable-debug-info --disable-docs --disable-werror \
  --meson=meson
ninja -j2 all meson-test-prereq
meson test --suite lat-pr-fast --no-rebuild --num-processes 2 \
  --print-errorlogs

• x86_64-linux-user lat-pr-fast: 31/31 passed.
• i386-linux-user lat-pr-fast: 21/21 passed.
• The TU and non-TU merge regressions read controlled cache files through the production merger and assert balanced allocations across success, replacement, duplicate input, and error paths. Generated AOT code publication remains stubbed.
• The segment-unmap regression invokes production target_munmap() with real host mappings. One range removes three segment/cache owners while preserving both neighbors; mincore() verifies the owned mappings were released. Invalid and repeated unmap are covered.
• A tests-disabled configuration registers none of the PR's test targets.
• git range-diff and stable patch IDs show the rebased commit is equivalent to the previously reviewed commit; author metadata, message, and Signed-off-by are preserved.

The current integration suite reports 34 skipped (exit 77): two lack the configured x86_64 guest sysroot, 26 lack Clang, and six lack x86_64-linux-gnu-gcc. These are not passes. No Wine application acceptance was run, and this PR does not claim full application memory acceptance.