Debugger: Make display of QObject names optional

... and switch it off by default. The feature has indeterministic
performance impact and lost quite a bit of its utility since GDB
learned to extract dynamic object types most of the times.

Change-Id: I22cccb03ba67f9ff6ad757bbc06eb372d84bbffe
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/debugger/gdb/gdbengine.cpp

@@ -4586,6 +4586,7 @@ void GdbEngine::doUpdateLocals(const UpdateParameters &params)
     cmd.arg("fancy", boolSetting(UseDebuggingHelpers));
     cmd.arg("autoderef", boolSetting(AutoDerefPointers));
     cmd.arg("dyntype", boolSetting(UseDynamicType));
+    cmd.arg("qobjectnames", boolSetting(ShowQObjectNames));
     cmd.arg("nativemixed", isNativeMixedActive());
 
     StackFrame frame = stackHandler()->currentFrame();