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

Note that rust-fuzz wrappers (including honggfuzz) already apply
this for us.

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index e4fe497fa3b6d3d8307d6392f6c2847751bdd6d2..628d620a5dc67cf048bd4e641ecb6c8e1dc16986 100644 (file)
--- a/.github/workflows/build.yml
+++ b/.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