Update llvm13 to version 13.0.1 / rev 18 via SR 1156033
    
    https://build.opensuse.org/request/show/1156033
    by user aaronpuchert + anag+factory
    - Explicitly define PYTHON3_EXECUTABLE, since python 3.11 is being
      pulled in by cmake in SLE-15-SP6.
    - Fix PowerPC triples: use powerpc[64[le]] instead of ppc[64[le]].
    - Disable test that fails on ppc64le.
    - Use %patch -P N instead of deprecated %patchN.