extension/amqp.control: No such file or directory

Hi,

I am running postgres 11-3-3 and with the AMQP extension but when I am activating it for a database via the 
CREATE EXTENSION statement I got 

```
could not open extension control file "/usr/share/postgresql/11/extension/amqp.control": No such file or directory
```

Is this library compatible with postgres11 or what can I do to solve that?

Thanks & regards

Olivier