RFR: 8336465: C2: EA incorrectly/unnecessarily checks for clinits [v2]

[Aleksey Shipilev]

> As shown in [JDK-8336103](https://bugs.openjdk.org/browse/JDK-8336103), EA code uses `is_initializer` where we expect to only check for constructors. This PR rewrites it appropriately. This nominally changes the EA behavior, but I do not think it would actually show up anywhere.
> 
> Additional testing:
>  - [x] Linux AArch64 server fastdebug, all (includes Fuzzer and CTW tests), passed as part of JDK-8336103 testing

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 two additional commits since the last revision:

 - Merge branch 'master' into JDK-8336465-c2-ea-obj-init
 - Fix

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20190/files
  - new: https://git.openjdk.org/jdk/pull/20190/files/245b9dd8..adf83026

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20190&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20190&range=00-01

  Stats: 4 lines in 2 files changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/20190.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20190/head:pull/20190

PR: https://git.openjdk.org/jdk/pull/20190