Bug 1512

- Using OpenJDK 21 (https://adoptium.net/temurin/releases/)
  - Java 11 Class-Files (was Java 8, but supported in Android SDK now)

- Build + Tests Nodes
  - MacOS 15.5 arm64 Sequoia: OK (test, build manually)
  - MacOS 12.6.5 x86_64 Monterey: OK (build/test)
    - x86_64, arm64
  - GNU/Linux Debian 12 Bookworm: OK (build/test)
    - x86_64, arm64, arm32
    - new crosstools-ng for arm64, arm32
      - Debian 11, gcc 12.4.0
  - Windows 10: OK 
    - x86_64
  - Android 
    - New SDK: NDK 29, build-tools 36 (as of 2025-06-01)
    - x86, x86_64, arm64, arm32 manually and disabled

  - GlueGen 
    - semver -> japicmd for Java >= 11 compatibility

  - JOAL's OpenAL-Soft
    - version bump 1.23.1 -> 1.24.3
    - requiring successful openal-soft build     

Tracking w/ further change details:
https://jogamp.org/wiki/index.php/SW_Tracking_Report_Objectives_for_the_release_2.6.0

First RC from 20250628:
https://jogamp.org/deployment/v2.6.0-rc-20250628/