doc: Fix some "Cannot tie this..." errors

These are errors where clangqdoc finds a qdoc comment, but
it can't find anything in the API to associate it with. There
are different causes. In many cases, soneone has documented a
function that isn't in the public API so it should not be
documented in the first place. In other cases, a function is
platform-specific and we need to add || defined(Q_CLANG_QDOC)
somewhere to make it visible.

Change-Id: I2b707548109f626e20d28f084072ef78f2ee6ac5
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

src/corelib/io/qdir.cpp

@@ -2087,6 +2087,7 @@ bool QDir::match(const QString &filter, const QString &fileName)
 #endif // QT_NO_REGEXP
 
 /*!
+    \internal
     Returns \a path with redundant directory separators removed,
     and "."s and ".."s resolved (as far as possible).
 

src/corelib/json/qjsondocument.cpp

@@ -332,7 +332,7 @@ QVariant QJsonDocument::toVariant() const
 
  \sa fromJson()
  */
-#ifndef QT_JSON_READONLY
+#if !defined(QT_JSON_READONLY) || defined(Q_CLANG_QDOC)
 QByteArray QJsonDocument::toJson() const
 {
     return toJson(Indented);
@@ -369,7 +369,7 @@ QByteArray QJsonDocument::toJson() const
 
     \sa fromJson(), JsonFormat
  */
-#ifndef QT_JSON_READONLY
+#if !defined(QT_JSON_READONLY) || defined(Q_CLANG_QDOC)
 QByteArray QJsonDocument::toJson(JsonFormat format) const
 {
     QByteArray json;

src/corelib/json/qjsondocument.h

@@ -131,9 +131,7 @@ public:
 
     static QJsonDocument fromJson(const QByteArray &json, QJsonParseError *error = nullptr);
 
-#ifdef Q_QDOC
-    QByteArray toJson(JsonFormat format = Indented) const;
-#elif !defined(QT_JSON_READONLY)
+#if !defined(QT_JSON_READONLY) || defined(Q_CLANG_QDOC)
     QByteArray toJson() const; //### Merge in Qt6
     QByteArray toJson(JsonFormat format) const;
 #endif