Bigger iovec buffer in ngx_readv_chain().
Bigger iovec buffer in ngx_readv_chain().

This helps to reduce likelyhood of memory allocations in ngx_readv_chain(),
which are known to lead to noticeable effects in some cases, see
http://mailman.nginx.org/pipermail/nginx/2014-July/044512.html.

hy0kl/nginx,hy0kl/nginx,hy0kl/nginx,firebase/nginx,firebase/nginx,firebase/nginx,firebase/nginx