Update libafl_libfuzzer (google#1888)

We recently updated libafl_libfuzzer in a lot of ways. This fetches the
current "release" revision and pins the Rust version.

fuzzers/libafl_libfuzzer/builder.Dockerfile

@@ -28,17 +28,15 @@ RUN apt-get update && \
 # Uninstall old Rust & Install the latest one.
 RUN if which rustup; then rustup self uninstall -y; fi && \
     curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs > /rustup.sh && \
-    sh /rustup.sh --default-toolchain nightly -y && \
+    sh /rustup.sh --default-toolchain nightly-2023-08-23 -y && \
     rm /rustup.sh
 
 # Download libafl.
-RUN git clone \
-        --branch libfuzzer \
-        https://github.com/AFLplusplus/libafl /libafl && \
+RUN git clone https://github.com/AFLplusplus/libafl /libafl && \
     cd /libafl && \
-    git checkout d31f82387d1d233771ff1e13ef7e49cdb508410f && \
+    git checkout defe9084aed5a80ac32fe9a1f3ff00baf97738c6 && \
     unset CFLAGS CXXFLAGS && \
     export LIBAFL_EDGES_MAP_SIZE=2621440 && \
     cd ./libafl_libfuzzer/libafl_libfuzzer_runtime && \
-    env -i CXX=$CXX CC=$CC PATH="/root/.cargo/bin/:$PATH" cargo build --release --no-default-features && \
-    cp ./target/release/libafl_libfuzzer_runtime.a /usr/lib/libFuzzer.a
+    env -i CXX=$CXX CC=$CC PATH="/root/.cargo/bin/:$PATH" cargo build --profile release-fuzzbench && \
+    cp ./target/release-fuzzbench/libafl_libfuzzer_runtime.a /usr/lib/libFuzzer.a