get rid of harmless error in verbose test

The `toy_build` unit tests are spitting our an error message because a specified easyconfig file is not found in the specified (relative) location.

```bash
$ PYTHONPATH=$PWD python test/framework/toy_build.py
.............== ERROR: Can't find path /Users/kehoste/work/easybuild-framework/gompi-1.4.10.eb

...
----------------------------------------------------------------------
Ran 16 tests in 265.835s

OK
```

The error is harmless since the easyconfig is actually found after all.
This patch fixes the it by specifying the absolute path to easyconfig file to be used.