Fix typo with impact on test output

If the test fails here, output the values actually used in comparison.

Change-Id: Ie4ed5ebdf1951c02b89a9648aee50a99d0bb0628
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

tests/auto/corelib/tools/qvector/tst_qvector.cpp

@@ -2308,7 +2308,7 @@ void tst_QVector::setSharable() const
         if (isCapacityReserved)
             QVERIFY2(copy.capacity() >= capacity,
                     qPrintable(QString("Capacity is %1, expected at least %2.")
-                        .arg(vector.capacity())
+                        .arg(copy.capacity())
                         .arg(capacity)));
         QCOMPARE(copy, vector);
     }