if item_storage_allocated is per-thread, we actually allocate (#thread) * memlimit
if item_storage_allocated is per-thread, we actually allocate (#thread) * memlimit

Summary: accumulate item_storage_allocated before reading.  this should happen infrequently enough that it won't kill system performance.

Reviewed By: ps

Test Plan: ran it with mcblaster cmdline:
           ./mcblaster -p 15151 -u 15151 -c 32 -k 1000000 -x 4 -w 50000 -r 50000 -z 8192 127.0.0.1
           
           resident memory went to about 100mb, but dropped back to ~66mb after i killed mcblaster.

Revert: OK


git-svn-id: d16fc8af3894fe4b8f00d9e752b9e158f74a7d75@126762 2c7ba8d8-a2f7-0310-a573-de162e16dcc7

sysalexis/memcached,sysalexis/memcached,sysalexis/memcached,sysalexis/memcached,sysalexis/memcached