[3.15] Avoid Clang bug in UBSan CI (GH-157958) (#158506)

Co-authored-by: Stan Ulbrych <stan@python.org>
Co-authored-by: Victor Stinner <vstinner@python.org>

Author: 3 people

.github/workflows/reusable-san.yml

@@ -90,10 +90,14 @@ jobs:
         --openssl="${OPENSSL_VER}"
         --system=Linux
         --tsan
+    # gh-157958: -O2 instead of the pydebug default -Og to avoid a clang 21
+    # compile-time blowup on some interpreter files.
+    # (https://github.com/llvm/llvm-project/issues/179695)
     - name: Configure CPython
       run: >-
         ./configure
         --config-cache
+        OPT="-O2 -g"
         ${{
           inputs.sanitizer == 'TSan'
           && '--with-thread-sanitizer'