run.dlang.io dmd version < 2.086 fail

[James Blachly]

The "All dmd compiler versions" is an incredibly useful part of the 
online editor/playground, but versions prior to 2.086.1 seem not to be 
installed correctly:

```
onlineapp.d(1): Error: module `std` is in file 'std.d' which cannot be read
import path[0] = /path/to/dmd.linux/dmd2/linux/bin64/../../src/phobos
import path[1] = 
/path/to/dmd.linux/dmd2/linux/bin64/../../src/druntime/import
```

whereas subsequent versions run (and succeed/fail as expected depending 
on code and features used)