Update LibAFL (google#2036)

Author: tokatoka

fuzzers/libafl/builder.Dockerfile

@@ -39,7 +39,7 @@ RUN wget https://gist.githubusercontent.com/tokatoka/26f4ba95991c6e3313999997633
 RUN git clone https://github.com/AFLplusplus/LibAFL /libafl
 
 # Checkout a current commit
-RUN cd /libafl && git pull && git checkout f3433767bea0cc3d7ee3b4c08be138e61d20c468 || true
+RUN cd /libafl && git pull && git checkout f856092f3d393056b010fcae3b086769377cba18 || true
 # Note that due a nightly bug it is currently fixed to a known version on top!
 
 # Compile libafl.