RFR: 8286117: Remove unnecessary indirection and unused code in UL [v2]

[Ioi Lam]

On Mon, 9 May 2022 11:15:40 GMT, Johan Sjölén <duke at openjdk.java.net> wrote:

>> This PR cleans up some minor annoyances in the UL code.
>> 
>> Note that the change from `LogImpl` to `LogTagSet` is equivalent, we're essentially inlining the calls that `LogImpl` would have made. This simplifies understanding ("why do we need `LogImpl` here?" was my question, answer: We don't!)'
>> 
>> *Edit:* Passes tier1.
>
> Johan Sjölén has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use _tagset

Marked as reviewed by iklam (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/8541