fix xcache.var_ttl displaying in info, fix xcache_get for ttl-unlimited
fix xcache.var_ttl displaying in info, fix xcache_get for ttl-unlimited

LTD-Beget/xcache,LTD-Beget/xcache,LTD-Beget/xcache,LTD-Beget/xcache,LTD-Beget/xcache