Add valgrind support for consumer

The tests/consumer-valgrind is a script that starts the session daemon
with valgrind support for the consumer. Output files are:

/tmp/valgrind.ust32consumer.log
/tmp/valgrind.ust64consumer.log
/tmp/valgrind.kconsumer.log

Signed-off-by: David Goulet <dgoulet@efficios.com>