Demo non deterministic errors in testsuite

[sloriot]

There are a couple of errors that we cannot reproduce locally and that only happen in the testsuite, also in non reproducible ways.

• strange link error

Polyhedron_3.cpp:(.text+0x7f): undefined reference to `Polyhedron_demo::Polyhedron_demo(int&, char**, QString, QString, QList<QString>)'
/usr/bin/ld: Polyhedron_3.cpp:(.text+0xb2): undefined reference to `Polyhedron_demo::try_exec()'
/usr/bin/ld: Polyhedron_3.cpp:(.text+0xc4): undefined reference to `Polyhedron_demo::~Polyhedron_demo()'
/usr/bin/ld: Polyhedron_3.cpp:(.text+0x116): undefined reference to `Polyhedron_demo::~Polyhedron_demo()'

• Only seen with qt6. A possible race condition?

  • https://cgal.geometryfactory.com/CGAL/testsuite/CGAL-6.0-Ic-113/Polyhedron_Demo/TestReport_lrineau_Debian-Stable.gz
  • https://cgal.geometryfactory.com/CGAL/testsuite/CGAL-6.0-Ic-113/Polyhedron_Demo/TestReport_lrineau_ArchLinux.gz

• An error also present with qt5. First seen in CGAL-5.6-Ic-274.

  • [test/AABB_tree_Demo/CMakeFiles/CGAL_Qt6_moc_and_resources.dir/build.make:206: test/AABB_tree_Demo/libCGAL_Qt6_moc_and_resources.a] Error 1
    ` for example here

[sloriot]

Fixed by #7915 and test platform update