TS-2190: remove cache.log from the cacheurl plugin

The information in the cacheurl plugin log is for debugging purposes,
but you can already get that from diagnostics.  Remove the log file
since it's not really useful and it's better to have fewer logfiles.
TS-2190: fix the -Werror build
TS-2251: simplify LogBuffer reference counting
[TS-1449] Update Doc to match actual default
TS-2432 fix a race in aio_err_callbck that may lead hash_table
can not rebuild.
TS-2335: add features for ts_lua

1) inject remap vars
2) free memory which is allocated by TSUrlStringGet
3) add ts.client_request.get_pristine_url()

Signed-off-by: Quehan <quehan@taobao.com>
Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>