RFR: Prefer to take AOT method from the SC queue faster [v2]

[Aleksey Shipilev]

> Probably WIP. Humor me for a second: why could not / should not we take the AOT task for "compilation" (installation, really) right away like this? I suspect when SC queues are overwhelmed with N elements, we keep walking the entire SC queue for no particular reason?
> 
> This improves javac benchmark considerably (look at both wall time and user time):
> 
> 
> # BEFORE
> Benchmark 1: build/linux-x86_64-server-release/images/jdk/bin/java -XX:CacheDataStore=app.cds -Xmx256m -Xms256m -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC -cp JavacBenchApp.jar JavacBenchApp 50
>   Time (mean ± σ):     348.3 ms ±   2.8 ms    [User: 949.0 ms, System: 101.4 ms]
>   Range (min … max):   344.0 ms … 355.3 ms    100 runs
> 
> # AFTER
> Benchmark 1: build/linux-x86_64-server-release/images/jdk/bin/java -XX:CacheDataStore=app.cds -Xmx256m -Xms256m -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC -cp JavacBenchApp.jar JavacBenchApp 50
>   Time (mean ± σ):     312.2 ms ±   2.6 ms    [User: 577.8 ms, System: 95.4 ms]
>   Range (min … max):   307.1 ms … 318.5 ms    100 runs

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Drop SCC check from comparator
 - Just return the SCC task right away
 - Merge branch 'premain' into shortcut-aot-tasks
 - Fix

-------------

Changes:
  - all: https://git.openjdk.org/leyden/pull/17/files
  - new: https://git.openjdk.org/leyden/pull/17/files/50ba10f4..c43c4516

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=leyden&pr=17&range=01
 - incr: https://webrevs.openjdk.org/?repo=leyden&pr=17&range=00-01

  Stats: 50 lines in 4 files changed: 24 ins; 5 del; 21 mod
  Patch: https://git.openjdk.org/leyden/pull/17.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/17/head:pull/17

PR: https://git.openjdk.org/leyden/pull/17