Fix a reason of *stopped notifications due to SIGINT/SIGSTOP signals (MI)

# Add SBProcess::GetInterruptedFromEvent
# Add vrEvent arg in CMICmnLLDBDebuggerHandleEvents::HandleProcessEventStateStopped
  and CMICmnLLDBDebuggerHandleEvents::HandleProcessEventStopSignal
# Refactor CMICmnLLDBDebuggerHandleEvents::HandleProcessEventStopSignal
## Clean up and fix typos
## Remove vwrbShouldBrk arg
# Fix MiSignalTestCase.test_lldbmi_stopped_when_stopatentry_{local,remote}
  to expect SIGSTOP instead of SIGINT

llvm-svn: 237426