Cache queries from block_block_info_alter()

Block modules currently issues two queries in block_block_info_alter(), they're the same on every request, relatively small (or null) result sets, and rarely changed, so a good candidate for caching. Also puts this in the cache_bootstrap() bin since it's information needed for every request (if block module is enabled).

HEAD:
Executed 63 queries in 44.48 milliseconds.

Patch:
Executed 62 queries in 47.26 milliseconds.

Only saves one query with database caching, but it's two if using memcache and they all add up.