Fix compile fail due to class/struct mismatch

Change-Id: Iac88272a968a202cbbc97b58df7dff7d48e62672
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/debugger/breakhandler.cpp

@@ -59,8 +59,9 @@ using namespace Utils;
 namespace Debugger {
 namespace Internal {
 
-struct LocationItem : public TreeItem
+class LocationItem : public TreeItem
 {
+public:
     QVariant data(int column, int role) const
     {
         if (role == Qt::DisplayRole) {