Network: Remove Q_DECL_METATYPE_EXTERN for single-.cpp metatypes

These were added in commit 20e6a049fee48e876c8c6903101b58f918b5aab2 as a
massive sweep of all Q_DECLARE_METATYPE, without thought as to whether
they were actually needed or not. If they are used as a metatype in a
single .cpp file, they don't need to be.

Incidentally removes the entirely incorrect Q_NETWORK_EXPORT of
QDnsLookupReply.

Pick-to: 6.5
Change-Id: I3e3bfef633af4130a03afffd175e6f378f09a3aa
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/access/qnetworkaccesscache.cpp

@@ -14,9 +14,6 @@
 
 QT_BEGIN_NAMESPACE
 
-QT_IMPL_METATYPE_EXTERN_TAGGED(QNetworkAccessCache::CacheableObject*,
-                               QNetworkAccessCache__CacheableObject_ptr)
-
 enum ExpiryTimeEnum {
     ExpiryTime = 120
 };

src/network/access/qnetworkaccesscache_p.h

@@ -87,7 +87,4 @@ private:
 
 QT_END_NAMESPACE
 
-QT_DECL_METATYPE_EXTERN_TAGGED(QNetworkAccessCache::CacheableObject*,
-                               QNetworkAccessCache__CacheableObject_ptr, /* not exported */)
-
 #endif

src/network/kernel/qdnslookup.cpp

@@ -13,8 +13,6 @@
 
 QT_BEGIN_NAMESPACE
 
-QT_IMPL_METATYPE_EXTERN(QDnsLookupReply)
-
 #if QT_CONFIG(thread)
 Q_GLOBAL_STATIC(QDnsLookupThreadPool, theDnsLookupThreadPool);
 #endif

src/network/kernel/qdnslookup_p.h

@@ -201,6 +201,4 @@ public:
 
 QT_END_NAMESPACE
 
-QT_DECL_METATYPE_EXTERN(QDnsLookupReply, Q_NETWORK_EXPORT)
-
 #endif // QDNSLOOKUP_P_H