Port AFL stuff from zcash upstream

zcutil/afl/afl-build.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+# A wrapper around ./zcutil/build.sh for instrumenting the build with AFL:
+#   ./zcutil/afl/afl-build.sh <directory where AFL is installed> <fuzz case>
+# You may obtain a copy of AFL using ./zcutil/afl/afl-get.sh.
+
+set -eu -o pipefail
+
+export AFL_INSTALL_DIR=$(realpath "$1")
+FUZZ_CASE="$2"
+shift 2
+export AFL_LOG_DIR="$(pwd)"
+export ZCUTIL=$(realpath "./zcutil")
+
+cp "./src/fuzzing/$FUZZ_CASE/fuzz.cpp" src/fuzz.cpp
+
+CONFIGURE_FLAGS="--enable-tests=no --enable-fuzz-main" "$ZCUTIL/build.sh" "CC=$ZCUTIL/afl/zcash-wrapper-gcc" "CXX=$ZCUTIL/afl/zcash-wrapper-g++" AFL_HARDEN=1 "$@"
+
+echo "You can now run AFL as follows:"
+echo "$ ./zcutil/afl/afl-run.sh '$AFL_INSTALL_DIR' '$FUZZ_CASE'"