Debugger: Simplify "debug last command"

Let the engine decide what to do. Less magic parsing, less code,
and survives cleaning the log view.

Change-Id: Ic94f27899d7986fb5ce3d24bb2edce8e6faf899c
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/debugger/gdb/gdbengine.cpp

@@ -5484,6 +5484,11 @@ QByteArray GdbEngine::dotEscape(QByteArray str)
     return str;
 }
 
+void GdbEngine::debugLastCommand()
+{
+    postCommand(m_lastDebuggableCommand, Discardable);
+}
+
 //
 // Factory
 //