Save locale cache time to storage?

[alvarogzp]

So that we can analyze its evolution.
But please take into account that locale_cache does not handle all locale caching. If a new locale directly performs a non empty query, it will generate localized data and cache it without locale_cache noticing.

Edit: Well, maybe there is no problem not saving all caching times, as when a query also caches a locale, its time will be too high that it can be easily spotted. If we did inject the storage api to the real cache, we would be slowing queries (although only queries that cache locales, they should not be too much, in fact, they should be almost zero due to preventive caching).