Log Message:
Updated afl to 2.23b.

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Version 2.23b:
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  - Improved the stability metric for persistent mode binaries. Problem
    spotted by Kurt Roeckx.

  - Made a related improvement that may bring the metric to 100% for those
    targets.

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Version 2.22b:
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  - Mentioned the potential conflicts between MSAN / ASAN and FORTIFY_SOURCE.
    There is no automated check for this, since some distros may implicitly
    set FORTIFY_SOURCE outside of the compiler's argv[].

  - Populated the support for AFL_LD_PRELOAD to all companion tools.

  - Made a change to the handling of ./afl-clang-fast -v. Spotted by
    Jan Kneschke.