Removed zero termination of shm zone names.

It was added in r2717 and no longer needed since r2721,
where the termination was added to ngx_shm_alloc() and
ngx_init_zone_pool().  So then it only corrupts error
messages about ivalid zones.


git-svn-id: svn://svn.nginx.org/nginx/trunk@5078 73f98a42-aea0-e011-b76d-00259023448c