Add a script for merging LICENSE files

.gitignore

@@ -1 +1,2 @@
 bazel-*
+MERGED_LICENSES

tools/BUILD

@@ -11,3 +11,8 @@ config_setting(
         "RELEASE": "devel",
     },
 )
+
+sh_binary(
+    name = "merge_licenses",
+    srcs = ["merge_licenses.sh"],
+)

tools/merge_licenses.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+set -o xtrace
+set -o errexit
+set -o nounset
+set -o pipefail
+
+output_path=${BUILD_WORKING_DIRECTORY}/MERGED_LICENSES
+# Truncate file.
+echo >"${output_path}"
+
+for path in $(find ${BUILD_WORKING_DIRECTORY}/vendor/ -name LICENSE); do
+  >&2 echo "adding ${path}";
+  # Trim working directory prefix from output.
+  cat <<EOF >>"${output_path}"
+-----------------------------------------------------------
+${path#"$BUILD_WORKING_DIRECTORY"}
+------------------------------------------------------------
+EOF
+  cat "${path}" >>"${output_path}"
+  echo >>"${output_path}"
+done