Add more fixes to clang 16.0
    
    1. Remove patches that are not necessary.
    2. Re-add a patch that generates DWARF4 by default.
    3. Add a patch fixing IEEE 128-bit long double tests on ppc64le.
    4. Include cmake code.
    5. Other minor issues.
    
    Part of these changes are heavily based on or copied from the work from
    Konrad Kleine in branch upstream-snapshot.