[mod_accesslog] %{ratio}n logs compression ratio (fixes #2133)
mod_deflate and mod_compress now provide data for mod_accesslog
"%{ratio}n%%" log format to log compression ratio
Implementation detail: compression ratio is stored in con->environment
since lighttpd does not currently have concept of module notes, which is
from where %{VARNAME}n originates. In the future, this might change in
lighttpd, so be sure to use %{ratio}n%% and not %{...}e for this info.
x-ref:
"accesslog support "%n" (compress ratio)"
https://redmine.lighttpd.net/issues/2133