Apply --cfg=fuzzing when fuzzing, as required by new secp256k1

Author: TheBlueMatt

.github/workflows/build.yml

@@ -202,7 +202,7 @@ jobs:
           sudo apt-get update
           sudo apt-get -y install build-essential binutils-dev libunwind-dev
       - name: Sanity check fuzz targets on Rust ${{ env.TOOLCHAIN }}
-        run: cd fuzz && cargo test --verbose --color always
+        run: cd fuzz && RUSTFLAGS="--cfg=fuzzing" cargo test --verbose --color always
       - name: Run fuzzers
         run: cd fuzz && ./ci-fuzz.sh
 

fuzz/ci-fuzz.sh

@@ -27,6 +27,7 @@ for TARGET in src/bin/*.rs; do
 		HFUZZ_RUN_ARGS="$HFUZZ_RUN_ARGS -N1000000"
 	fi
 	export HFUZZ_RUN_ARGS
+	export RUSTFLAGS="--cfg=fuzzing"
 	HFUZZ_BUILD_ARGS="--features honggfuzz_fuzz" cargo --color always hfuzz run $FILE
 	if [ -f hfuzz_workspace/$FILE/HONGGFUZZ.REPORT.TXT ]; then
 		cat hfuzz_workspace/$FILE/HONGGFUZZ.REPORT.TXT