Gzip: fixed zlib memLevel adjusting.
Gzip: fixed zlib memLevel adjusting.

An incorrect memLevel (lower than 1) might be passed to deflateInit2() if the
"gzip_hash" directive is set to a value less than the value of "gzip_window"
directive. This resulted in "deflateInit2() failed: -2" alert and an empty
reply.

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