RFR: 8303082 : [AIX] Missing C++ name demangling with XLClang++ [v6]

[Deepa Kumari]

> It was failing as It was using the C++ demangling interface (Demangle) of the old demangler (that is, the C++ API as opposed to the C one). It is not supported by xlclang++ on AIX.
> To demangle names generated by xlclang++ , use cxxabi.h __cxa_demangle interface ( see cxxabi.h).
> 
> This Solution applies to the following test 
> 
> 1. SecondaryErrorTest.java`
> 2. TestSigInfoInHsErrFile.java
> 
> 
> Reported Issue : [JDK - 8303082](https://bugs.openjdk.org/browse/JDK-8303082)

Deepa Kumari has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains three new commits since the last revision:

 - Remove free scope
 - Revert "8303082 : [AIX] Missing C++ name demangling with XLClang++"
   
   This reverts commit bd602ab9c463e549c4adb307a9f69c5b68d71eea.
 - 8303082 : [AIX] Missing C++ name demangling with XLClang++

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12742/files
  - new: https://git.openjdk.org/jdk/pull/12742/files/71107a5b..597515c2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12742&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12742&range=04-05

  Stats: 202930 lines in 2958 files changed: 43274 ins; 135309 del; 24347 mod
  Patch: https://git.openjdk.org/jdk/pull/12742.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/12742/head:pull/12742

PR: https://git.openjdk.org/jdk/pull/12742