Since a few versions lldb has had a tendency to remain stuck after the initial connection to the crashed application (on Mac). On Linux it would often exit cleanly and quickly in a way not foreseen by my previous code, causing DrKonqi to report an unexpected debugger termination.

This patch addresses both issues:

• recent lldb versions have no more problems with reading commands from a batchfile
• this make it possible to add an explicit exit command
• slotProcessExited() is called explicitly when lldb has confirmed the exit command
• errors caused by terminating or killing the debugger process are now ignored.

Getting a crash backtrace now works as expected on Mac and Linux. No regressions are introduced when using the gdb backend on Linux.