Support NPM versions that don't export config environment variables

The automatic exportation of environment variables based on the config key
in package.json was removed in later versions of Node.js. Here, we
manually set the environment variable if it's not automatically set.

Author: ptomato

scripts/export_npm_env.sh

@@ -1,4 +1,7 @@
 #!/bin/bash -e
+
+npm_package_config_V8=${npm_package_config_V8:-$(node -p 'require("./package.json").config.V8')}
+
 if [[ ${CIRCLECI} ]]; then
   echo "export VERSION=${npm_package_version}" >> $BASH_ENV
   echo "export V8_VERSION=${npm_package_config_V8}" >> $BASH_ENV