Remove redundant break;s following return;s

Pointed out by the INTEGRITY compiler.

Change-Id: Id5f9b994c348308c56c3a25200419be525b9c933
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

src/corelib/kernel/qmetacontainer.h

@@ -299,10 +299,8 @@ class QMetaContainerForContainer
                     return new Iterator;
                 case QMetaContainerInterface::AtBegin:
                     return new Iterator(static_cast<C *>(c)->begin());
-                    break;
                 case QMetaContainerInterface::AtEnd:
                     return new Iterator(static_cast<C *>(c)->end());
-                    break;
                 }
                 return nullptr;
             };