build: Add postbuild script for fuzzing

tests/fuzz/oss_fuzz_postbuild.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+# Copyright 2022 The Flux authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -euxo pipefail
+
+# This file is executed by upstream oss-fuzz after its building process.
+# Use it for unsetting any environment variables that may impact other building
+# processes.
+
+unset TARGET_DIR
+unset CGO_ENABLED
+unset LIBRARY_PATH
+unset PKG_CONFIG_PATH
+unset CGO_CFLAGS
+unset CGO_LDFLAGS
+unset ADDITIONAL_LIBS