Update afl to rev 51 via SR 805787
    
    https://build.opensuse.org/request/show/805787
    by user msmeissn + dimstar_suse
    - updated to 2.65c
      - afl-fuzz:
         - AFL_MAP_SIZE was not working correctly
         - better python detection
         - an old, old bug in afl that would show negative stability in rare
           circumstances is now hopefully fixed
         - AFL_POST_LIBRARY was deprecated, use AFL_CUSTOM_MUTATOR_LIBRARY
           instead (see docs/custom_mutators.md)
      - llvm_mode:
         - afl-clang-fast/lto now do not skip single block functions. This
           behaviour can be reactivated with AFL_LLVM_SKIPSINGLEBLOCK
         - if LLVM 11 is installed the posix shm_open+mmap is used and a fixed
           address for the shared memory map is used as this increases the
           fuzzing speed
         - InsTrim now has an LTO version! :-) That is the best and fastest mode!
         - fixes to LTO mode if instrumented edges > MAP_SIZE