QMetaObject: move QMetaMethodPrivate into an unnamed namespace

So the compiler doesn't feel like it must emit these functions. They're
not used outside of qmetaobject.cpp.

Change-Id: I36b24183fbd041179f2ffffd170228c6e94b5f9b
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/corelib/kernel/qmetaobject.cpp

@@ -164,6 +164,7 @@ static inline int typeFromTypeInfo(const QMetaObject *mo, uint typeInfo)
     return QMetaType::fromName(rawStringData(mo, typeInfo & TypeNameIndexMask)).id();
 }
 
+namespace {
 class QMetaMethodPrivate : public QMetaMethod
 {
 public:
@@ -215,6 +216,7 @@ public:
 private:
     QMetaMethodPrivate();
 };
+} // unnamed namespace
 
 enum { MaximumParamCount = 11 }; // up to 10 arguments + 1 return value
 

src/corelib/kernel/qmetaobject.h

@@ -150,6 +150,7 @@ private:
     static QMetaMethod fromRelativeMethodIndex(const QMetaObject *mobj, int index);
     static QMetaMethod fromRelativeConstructorIndex(const QMetaObject *mobj, int index);
 
+protected:
     struct Data {
         enum { Size = 6 };
 
@@ -169,7 +170,6 @@ private:
 
     const QMetaObject *mobj;
     Data data;
-    friend class QMetaMethodPrivate;
     friend struct QMetaObject;
     friend struct QMetaObjectPrivate;
     friend class QObject;

src/corelib/kernel/qmetaobject_p.h

@@ -131,7 +131,7 @@ Q_DECLARE_TYPEINFO(QArgumentType, Q_RELOCATABLE_TYPE);
 
 typedef QVarLengthArray<QArgumentType, 10> QArgumentTypeArray;
 
-class QMetaMethodPrivate;
+namespace { class QMetaMethodPrivate; }
 
 struct QMetaObjectPrivate
 {