Fix: Missing rcu read side lock in consumer

Fix: Missing rcu read side lock in consumer

The metadata thread was not using rcu read side lock for its operations
on the internal metadata hash table.

This led to faulty free() when destroying the hash table and possible
corrupted data when it was resized.

Also change some static definition of calls inside consumer.c.

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