small logger code clarity improvements
small logger code clarity improvements

put header sections for utils/bgthread/api, edit function names slightly so
it's clear what's only called from the bgthread.

remaining FIXME/TODO's appear noncritical. might do those in the future.

gencer/memcached,samanbarghi/memcached,dormando/memcached,rmccullagh/memcached,gencer/memcached,memcached/memcached,memcached/memcached,elfchief/memcached,memcached/memcached,samanbarghi/memcached,gencer/memcached,dormando/memcached,dormando/memcached,gencer/memcached,memcached/memcached,rmccullagh/memcached,bpzhang/memcached,rmccullagh/memcached,bpzhang/memcached,guikcd/memcached,samanbarghi/memcached,elfchief/memcached,dormando/memcached,dormando/memcached,bpzhang/memcached,guikcd/memcached,elfchief/memcached,guikcd/memcached,guikcd/memcached,guikcd/memcached,bpzhang/memcached,samanbarghi/memcached,rmccullagh/memcached,elfchief/memcached,rmccullagh/memcached,memcached/memcached,gencer/memcached,elfchief/memcached