Change the name of some tcmalloc stats
Change the name of some tcmalloc stats

We plan on having the ability to be able to track allocations
with different allocator and as a result it doesn't make sense
to have a different set of stats names for specific stats
depending on which allocator is used. For example, every allocator
has keeps track of bytes allocated, the size of the heap, how many
free bytes it has, and how much fragmentation it has caused. These
stats should have more general names.

tcmalloc_allocated_bytes -> total_allocated_bytes
tcmalloc_heap_size       -> total_heap_size
tcmalloc_free_bytes      -> total_free_bytes

Change-Id: I87fd8945591bce20d6de58a25c265efd66e78800
Reviewed-on: http://review.couchbase.org/14541
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Tested-by: Michael Wiederhold <a17fed27eaa842282862ff7c1b9c8395a26ac320@couchbase.com>

cloudrain21/memcached-1,cloudrain21/memcached-1,jimwwalker/memcached,couchbase/memcached,couchbase/memcached,owendCB/memcached,mrkwse/memcached,daverigby/kv_engine,owendCB/memcached,mrkwse/memcached,daverigby/memcached,abhinavdangeti/memcached,daverigby/kv_engine,couchbase/memcached,jimwwalker/memcached,daverigby/memcached,cloudrain21/memcached-1,couchbase/memcached,cloudrain21/memcached-1,abhinavdangeti/memcached,jimwwalker/memcached,abhinavdangeti/memcached,abhinavdangeti/memcached,mrkwse/memcached,daverigby/kv_engine,daverigby/memcached,daverigby/memcached,daverigby/kv_engine,abhinavdangeti/memcached,mrkwse/memcached,owendCB/memcached,owendCB/memcached