function createPackageConfig() {
    const retv = {}
    const packageName = process.env.npm_package_name
    if (!packageName) {
        return retv
    }

    for (const key of Object.keys(process.env)) {
        const m = PACKAGE_CONFIG_PATTERN.exec(key)
        if (m != null) {
            overwriteConfig(retv, packageName, m[1], process.env[key])
        }
    }

    return retv
}
Creates a package config object.
This checks `process.env` and creates the default value.

@returns {object} Created config object.