set cpuLayout at top of testIssue21 unit test

On my system (4-core AMD processor) the cpu layout specified for `dumpLocksCoreDuo()` was causing a test failure in the subsequent `testIssue21()` test.  Resetting the layout to the default fixes the issue.  Another way to fix the tests on my machine was to move `testIssue21()` and `testIssue19()` to the beginning of `AffinityLockTest`.

This may fix https://github.com/peter-lawrey/Java-Thread-Affinity/issues/39, hard to tell without more detail on that issue.