[split] util-core: optimizations in Buf
[split] util-core: optimizations in Buf

Problem

Buf is a low-level building block and can be optimized.

Solution

* Buf.ByteArray: Optimized `equals`.
* ConcatBuf: Remove allocations from `length`.

Result

Less object allocations for all.

RB_ID=431099

stremlenye/util,LitmusHealth/twitter-utils,edombowsky/util,LitmusHealth/twitter-utils,twitter/util,folone/util,tenghuihua/util,tenghuihua/util,twitter/util,luciferous/util,travisbrown/util,travisbrown/util,cogitate/twitter-util-uuid,nkhuyu/util,slackhappy/util,tenghuihua/util,cogitate/twitter-util-uuid,slackhappy/util,folone/util,luciferous/util,stremlenye/util,RUNDSP/util,wuqiangxjtu/util,nkhuyu/util,RUNDSP/util,nkhuyu/util,BuoyantIO/twitter-util,edombowsky/util,LitmusHealth/twitter-utils,LitmusHealth/twitter-utils,hydro2k/util,RUNDSP/util,hydro2k/util,slackhappy/util,tdyas/util,wuqiangxjtu/util,folone/util,nkhuyu/util,stremlenye/util,luciferous/util,folone/util,travisbrown/util,BuoyantIO/twitter-util,hydro2k/util,RUNDSP/util,wuqiangxjtu/util,stremlenye/util,travisbrown/util,hydro2k/util,cogitate/twitter-util-uuid,Jiri-Kremser/util,wuqiangxjtu/util,edombowsky/util,edombowsky/util,twitter/util,Jiri-Kremser/util,tenghuihua/util,Jiri-Kremser/util,BuoyantIO/twitter-util,BuoyantIO/twitter-util,tdyas/util,Jiri-Kremser/util,tdyas/util,tdyas/util,slackhappy/util,luciferous/util,cogitate/twitter-util-uuid