If a class has been forward declared we might not end up
inside the real class declaration when trying to find
declared test functions. So, do not just take the first
found symbol into account, continue to process others if
we haven't found the real declaration.

Task-number: QTCREATORBUG-19319
Change-Id: I752d7a10470f5362e2214596966d93c037d58f4a
Reviewed-by: David Schulz <david.schulz@qt.io>