...when the cdb got hung up.

Handle abort like in almost any debugger engine, first kindly
ask to quit. If this doesn't work kill the debugger process.

Task-number: QTCREATORBUG-13173
Change-Id: I1ddc98b1ffe00342c96d104c16099b500e52bc07
Reviewed-by: hjk <hjk121@nokiamail.com>