hotfix(galileo) use cache shm for retry policy

4720b7b renamed the previous 'locks' shm and broke the galileo retry
policy relying on it. To avoid users to modify their nginx config if
they use a custom one, this makes galileo use the already present (and
huge) 'cache' shm.

kong/plugins/mashape-analytics/buffer.lua

@@ -48,7 +48,7 @@ local EMPTY_ARRAY_PLACEHOLDER = "__empty_array_placeholder__"
 -- The policy will give a delay that grows everytime
 -- Galileo fails to respond. As soon as Galileo responds,
 -- the delay is reset to its base.
-local dict = ngx.shared.locks
+local dict = ngx.shared.cache
 local RETRY_INDEX_KEY = "mashape_analytics_retry_index"
 local RETRY_BASE_DELAY = 1 -- seconds
 local RETRY_MAX_DELAY = 60 -- seconds