Introduce def as a trial. Fixup of timeit.

.github/workflows/main.yml

@@ -268,7 +268,7 @@ jobs:
           python3 src/tester.py ../build/c3c test_suite/
 
       - name: bundle_output
-        if: matrix.llvm_version == env.LLVM_RELEASE_VERSION
+        if: matrix.llvm_version == 16
         run: |
           mkdir linux
           cp -r lib linux
@@ -277,7 +277,7 @@ jobs:
           tar czf c3-linux-${{matrix.build_type}}.tar.gz linux
 
       - name: upload artifacts
-        if: matrix.llvm_version == env.LLVM_RELEASE_VERSION
+        if: matrix.llvm_version == 16
         uses: actions/upload-artifact@v3
         with:
           name: c3-linux-${{matrix.build_type}}