QArrayDataPointer: add missing Q_CHECK_PTR check in assign()

The previous implementation of iterator-assign did not include a check
for the return value of QArrayData::allocate(~), which returns a nullptr
on failure.

Amends: bbbe5f45c4.

Change-Id: I219e63ecd6de4225364d9c3dd2006ddbbe47068f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

src/corelib/tools/qarraydatapointer.h

@@ -320,10 +320,12 @@ public:
             const qsizetype n = std::distance(first, last);
             if (needsDetach() || n > constAllocatedCapacity()) {
                 QArrayDataPointer allocated(Data::allocate(detachCapacity(n)));
+                Q_CHECK_PTR(allocated.data());
                 swap(allocated);
             }
         } else if (needsDetach()) {
             QArrayDataPointer allocated(Data::allocate(allocatedCapacity()));
+            Q_CHECK_PTR(allocated.data());
             swap(allocated);
             // We don't want to copy data that we know we'll overwrite
         }