DSHM useless call to setmetadata when pool is specified

[oldium]

DSHM constructor calls setmetadata when pool value is specified but ignores the result.

See

lua-resty-session/lib/resty/session/dshm.lua

Lines 311 to 345 in 8b5f875

	if pool or pool_size or backlog then
	setmetatable({
	prefix = prefix,
	suffix = suffix,
	host = host,
	port = port,
	connect_timeout = connect_timeout,
	send_timeout = send_timeout,
	read_timeout = read_timeout,
	keepalive_timeout = keepalive_timeout,
	ssl = ssl,
	ssl_verify = ssl_verify,
	server_name = server_name,
	options = {
	pool = pool,
	pool_size = pool_size,
	backlog = backlog,
	}
	}, metatable)
	end
	return setmetatable({
	prefix = prefix,
	suffix = suffix,
	host = host,
	port = port,
	connect_timeout = connect_timeout,
	send_timeout = send_timeout,
	read_timeout = read_timeout,
	keepalive_timeout = keepalive_timeout,
	ssl = ssl,
	ssl_verify = ssl_verify,
	server_name = server_name,
	}, metatable)
	end

[bungle]

good catch! thanks!