hadrian: Reduce verbosity on failed testsuite runwip/hadrian-testsuite-exit

When the testsuite failed before it would print a big exception which
gave you the very long command line which was used to invoke the
testsuite. By capturing the exit code and rethrowing the exception, the
error is must less verbose:

```
Error when running Shake build system:
  at want, called at src/Main.hs:104:30 in main:Main
* Depends on: test
* Raised the exception:
user error (tests failed)
```

0 files changed, 0 insertions, 0 deletions