QJNI: optimize QSharedPointer creation

Instead of QSharedPointer<T>(new T), use QSharedPointer<T>::create(), since the latter
co-locates the refcount and the T instance in a single memory allocation, unlike the
first form, which uses separate memory allocations.

Change-Id: I5095ac43448aad9a7e3ec07ed4dcdca869bcd9e8
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

src/corelib/kernel/qjni_p.h

@@ -177,7 +177,7 @@ public:
     {
         jobject jobj = static_cast<jobject>(o);
         if (!isSameObject(jobj)) {
-            d = QSharedPointer<QJNIObjectData>(new QJNIObjectData());
+            d = QSharedPointer<QJNIObjectData>::create();
             if (jobj) {
                 QJNIEnvironmentPrivate env;
                 d->m_jobject = env->NewGlobalRef(jobj);