GLIBC_2.18 not found

## Issue or Feature

Upgrade `canvas` version `2.8.0`, throw error when starting node.js application, the error message:
```bash
error: /lib64/libc.so.6: version `GLIBC_2.18` not found (required by ...(project_dir).../node_modules/_canvas@2.8.0@canvas/build/Release/librsvg-2.so.2)
```
But, lock the `canvas` version ` 2.7.0`, work well.

## Steps to Reproduce

```js
var Canvas = require('canvas');
```

## Your Environment
* canvas@2.8.0
* node 10.x on CentOS 7: