clisp testing on linux

[Robert Goldman]

The latest tweak was followed by a Jenkins (linux) test failure for 
clisp on `test-encodings.script`, with a segmentation fault.

I cannot reliably replicate this, and I don't see any reason to assume 
that this is ASDF's fault, rather than clisp's.

I'm not sure that there is anything I can do about this, but thought I 
would ask for suggestions:

```
Test TEST-FILE-ENCODING-U8: should be UTF-8
; Registering system test-file-encoding-u8

*** - handle_fault error2 ! address = 0x55f6cc8871d0 not in 
[0x55db332bd000,0x55db336926d8) !
SIGSEGV cannot be cured. Fault address = 0x55f6cc8871d0.
GC count: 203
Space collected by GC: 304757408
Run time: 3 915662
Real time: 4 586182
GC time: 0 693431
Permanently allocated: 165368 bytes.
Currently in use: 8753400 bytes.
Free space: 1903262 bytes.
Segmentation fault (core dumped)
Using clisp, test-encodings.script failed
```

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.common-lisp.net/pipermail/asdf-devel/attachments/20181218/afc5cd4b/attachment.html>