Update llvm13 to version 13.0.1 / rev 11 via SR 1001714
    
    https://build.opensuse.org/request/show/1001714
    by user aaronpuchert + dimstar_suse
    - Make sure we keep -DNDEBUG. At some point %{optflags} must have
      lost it, perhaps because CMake usually adds it on top. So when
      overriding CMAKE_{C,CXX}_FLAGS_RELWITHDEBINFO, we make sure to
      take over the other flags. We drop LLVM_ENABLE_ASSERTIONS=OFF,
      because that's the default anyway and hasn't helped here.
    - Add llvm-glibc-2-36.patch in order to address boo#1202215.