Remove unused forward declaration

src/mail/mailmanager.h

@@ -6,11 +6,9 @@
 namespace Akonadi
 {
 class CollectionFilterProxyModel;
-class EntityMimeTypeFilterModel;
 class Session;
 }
 
-class QAbstractListModel;
 class QItemSelectionModel;
 
 class MailModel;

src/mail/mime/messageparser.h

@@ -16,11 +16,6 @@ class QAbstractItemModel;
 
 class MessagePartPrivate;
 
-namespace MimeTreeParser
-{
-class ObjectTreeParser;
-}
-
 class MessageParser : public QObject
 {
     Q_OBJECT

src/mail/mimetreeparser/messagepart.h

@@ -11,8 +11,6 @@
 #include <QSharedPointer>
 #include <QString>
 
-class QTextCodec;
-
 namespace KMime
 {
 class Content;