RFR: 8355636: Reuse StringBuilder in printStackTrace [v7]

[Shaojin Wen]

> In the Throwable::printStackTrace method, StringBuilder is created multiple times to build String. By sharing StringBuilder to build String, object allocation and copying are reduced.
> 
> In the scenario without suppressed and ourCause, unused IdentityHashMap is not created.
> 
> Through these optimizations, the performance of `new Exception().printStackTrace()` can be improved by about 10%.

Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:

  Update src/java.base/share/classes/java/lang/Throwable.java
  
  Co-authored-by: Hendrik Schick <30866028+ky0n at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24864/files
  - new: https://git.openjdk.org/jdk/pull/24864/files/6160f403..6bbe90f6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24864&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24864&range=05-06

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24864.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24864/head:pull/24864

PR: https://git.openjdk.org/jdk/pull/24864