Update afl to 2.05b:

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Version 2.05b:
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  - Put __sanitizer_cov_module_init & co behind #ifdef to avoid problems
    with ASAN. Spotted by Christian Holler.

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Version 2.04b:
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  - Removed indirect-calls coverage from -fsanitize-coverage (since it's
    redundant). Spotted by Kostya Serebryany.

(wiz)