Valgrind testing not functional

./configure --enable-valgrind-tests && make check should perform valgrind testing, but it doesn't.

Valgrinding takes a lot of time, e.g. when doing it manually:

./configure --enable-valgrind-tests
make check
cd tests
valgrind ./test-lookup

TESTS_ENVIRONMENT="valgrind" make check doesn't work either. Something is severely broken...