Empty string after strip with opening block comment symbol inside of a comment

If a camper writes code like:

```js
/**
* Some comment text
* example.com/*
*/

let hello = 'world';
console.log(hello);
`
```

All they will end up left with is an empty string.

I think we need a way for block comment characters to be escaped when they're already inside of a block comment.

Issue noted from: https://github.com/jonschlinkert/strip-comments/issues/51