As we are still constructing build system target to compare with
on the test runner's side instead of getting the complete
information from the run configuration we ended up using the wrong
one in several circumstances. Avoid this by using the executable
information we already got.

Task-number: QTCREATORBUG-17783
Change-Id: I40431bef228f7070109297873c472fea410dbd16
Reviewed-by: David Schulz <david.schulz@qt.io>