Mark Q_UNUSED the private members that aren't used

Apple Clang 4.2 has a new warning, letting you know when a private
member isn't used by any member function (and, I guess, if the class
has no friends):

  private field 'd' is not used [-Werror,-Wunused-private-field]

Qt has a few of those for future expansion. It's not an error for us.

Change-Id: Id2edb1159589572f97a07f93181c9c96c5dd983c
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: David Faure <david.faure@kdab.com>

src/corelib/kernel/qabstractnativeeventfilter.cpp

@@ -61,6 +61,7 @@ QT_BEGIN_NAMESPACE
 */
 QAbstractNativeEventFilter::QAbstractNativeEventFilter()
 {
+    Q_UNUSED(d);
 }
 
 /*!

src/corelib/tools/qbytearraymatcher.cpp

@@ -164,6 +164,7 @@ QByteArrayMatcher::QByteArrayMatcher(const QByteArrayMatcher &other)
 */
 QByteArrayMatcher::~QByteArrayMatcher()
 {
+    Q_UNUSED(d);
 }
 
 /*!

src/corelib/tools/qstringmatcher.cpp

@@ -198,6 +198,7 @@ QStringMatcher::QStringMatcher(const QStringMatcher &other)
 */
 QStringMatcher::~QStringMatcher()
 {
+    Q_UNUSED(d_ptr);
 }
 
 /*!

src/corelib/tools/qtextboundaryfinder.cpp

@@ -229,6 +229,7 @@ QTextBoundaryFinder &QTextBoundaryFinder::operator=(const QTextBoundaryFinder &o
 */
 QTextBoundaryFinder::~QTextBoundaryFinder()
 {
+    Q_UNUSED(unused);
     if (freePrivate)
         free(d);
 }