Install AOCC on Ubuntu 26.04 without the libxml2 dependency

[djkees]

Fix compiler: aocc on Ubuntu 26.04 (ubuntu-latest moves there on 2026-10-19), where dpkg -i fails on the .deb's Depends: libxml2.

• Ubuntu 26.04 renamed libxml2 to libxml2-16 and nothing provides libxml2, so the dependency can never be satisfied and apt-get install -f can't repair it
• No AOCC binary links libxml2 (checked readelf -d on every ELF file in the 5.2 package), so the dependency is spurious
• On Ubuntu 26+ the installer now installs the real runtime dependencies with apt, unpacks the .deb with dpkg-deb -x, and copies the /opt/AMD tree into place; the package has no maintainer scripts
• Ubuntu 24.04 and 22.04 keep the existing dpkg -i + apt-get install -f path
• Tested 5.2 and 4.1 on ubuntu-26.04 (install, verify-installation and integration tests pass)