Analyzer: Trigger stopIt() only once when pressing the stop button

The stopIt() slot is already connected in the constructor of
AnalyzerRunControl.

The double connection is clearly not intended and, considering that
various analyzers modify internal state from those callse, could lead
to incorrect behavior.

Change-Id: I1c68eb06729849771f4a25257a219c84a032adf3
Reviewed-by: hjk <hjk121@nokiamail.com>