Tests: use libtool wrapper to improve valgrind integration

Use libtool --mode=execute in the Valgrind wrapper to avoid analyzing
the libtool-generated shell script. This ensures that only the actual
test binaries are traced by Valgrind, reducing noise from unrelated
memory allocations made by the shell and improving the accuracy of
memory leak reports.

Author: olszomal

tests/common.sh

@@ -20,7 +20,7 @@
 # Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
 # Uncomment the following line to enable debugging with Valgrind
-# WRAPPER="valgrind -s --track-origins=yes --leak-check=full --show-leak-kinds=all --tool=memcheck --show-reachable=yes --keep-debuginfo=yes"
+# WRAPPER="libtool --mode=execute valgrind -s --track-origins=yes --leak-check=full --show-leak-kinds=all --tool=memcheck --show-reachable=yes --keep-debuginfo=yes"
 
 echo "Current directory: $(pwd)"
 echo "Source directory: ${srcdir}"