Work around arm64 clang codegen issues breaking CI

Disable preserve_none under ASan on aarch64: every clang tested (20,
21, trunk 22) miscompiles the continuation chains with that
combination, crashing ~97% of fuzz corpus tests. The chains still work
with the default calling convention. See #38.

Mark the masked Node3 scan results defined for valgrind on aarch64:
clang 21+ lowers the in-bounds tests through flags+csel, which
memcheck models imprecisely, tainting bits the mask provably clears.
See #39.

Skip valgrind tests in the arm64 release job, since -DNVALGRIND
compiles out the client requests the workaround relies on.

Both issues track filing upstream bugs.

.gitea/workflows/ci.yml

@@ -149,7 +149,11 @@ jobs:
       - name: Test
         run: |
           cd build
-          ctest --no-compress-output --test-output-size-passed 100000 --test-output-size-failed 100000 -T Test -j "$(nproc)" --timeout 90 > /dev/null
+          # On arm64, valgrind needs the MAKE_MEM_DEFINED client requests for
+          # https://git.weaselab.dev/weaselab/conflict-set/issues/39, but this
+          # build has -DNVALGRIND, which compiles them out. Skip valgrind
+          # tests here; they run annotated in the test job.
+          ctest --no-compress-output --test-output-size-passed 100000 --test-output-size-failed 100000 ${{ matrix.arch == 'arm64' && '-E valgrind' || '' }} -T Test -j "$(nproc)" --timeout 90 > /dev/null
 
       - name: Package
         run: |