RFR: JDK-8322648: Improve class initialization barrier in TemplateTable::_new for PPC [v3]

[Varada M]

> ppc port implementation of https://github.com/openjdk/jdk/pull/17006
> 
> Fastdebug and Release : build and tier1 testing successful.
> 
> JBS Issue : [JDK-8322648](https://bugs.openjdk.org/browse/JDK-8322648)

Varada M has updated the pull request incrementally with one additional commit since the last revision:

  8322648: Improve class initialization barrier in TemplateTable::_new for PPC

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17518/files
  - new: https://git.openjdk.org/jdk/pull/17518/files/2fb4cc08..e85eb148

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17518&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17518&range=01-02

  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/17518.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17518/head:pull/17518

PR: https://git.openjdk.org/jdk/pull/17518