Doc: Use \relates for functions in the global scope

This addresses the recent warnings introduced by a change to QDoc:

qkeysequence.h:32: (qdoc) warning: No documentation generated for
    function 'qHash' in global scope.
qmap.h:1557: (qdoc) warning: No documentation generated for function
    'operator+' in global scope.
qmap.h:1565: (qdoc) warning: No documentation generated for function
    'operator+=' in global scope.
qvariant.h:582: (qdoc) warning: No documentation generated for
    function 'operator>>' in global scope.
qvariant.h:590: (qdoc) warning: No documentation generated for
    function 'operator<<' in global scope.

Also, mark qt_win_hasPackageIdentity() declared in qfunctions_win_p.h
as \internal.

Pick-to: 6.5
Change-Id: Idc9c813370ff3133ac9dc3bf809976b0ece88811
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

src/corelib/kernel/qfunctions_win.cpp

@@ -33,6 +33,7 @@ QComHelper::~QComHelper()
 }
 
 /*!
+    \internal
     Checks if the application has a \e{package identity}
 
     Having a \e{package identity} is required to use many modern

src/corelib/kernel/qvariant.cpp

@@ -1294,12 +1294,14 @@ QDataStream &operator<<(QDataStream &s, const QVariant &p)
 }
 
 /*! \fn QDataStream& operator>>(QDataStream &s, QVariant::Type &p)
+    \relates QVariant
     \deprecated [6.0] Stream QMetaType::Type instead.
 
     Reads a variant type \a p in enum representation from the stream \a s.
 */
 
 /*! \fn QDataStream& operator<<(QDataStream &s, const QVariant::Type p)
+    \relates QVariant
     \deprecated [6.0] Stream QMetaType::Type instead.
 
     Writes a variant type \a p to the stream \a s.

src/corelib/tools/qmultimap.qdoc

@@ -959,6 +959,7 @@
 */
 
 /*! \fn template <class Key, class T> QMultiMap<Key, T> operator+=(QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)
+    \relates QMultiMap
 
     Inserts all the items in the \a rhs map into the \a lhs map and
     returns the resulting map.
@@ -967,6 +968,7 @@
 */
 
 /*! \fn template <class Key, class T> QMultiMap<Key, T> operator+(const QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)
+    \relates QMultiMap
 
     Returns a map that contains all the items in the \a lhs map in
     addition to all the items in \a rhs. If a key is common to both

src/gui/kernel/qkeysequence.cpp

@@ -1427,6 +1427,7 @@ bool QKeySequence::operator==(const QKeySequence &other) const
 
 /*!
     \since 5.6
+    \relates QKeySequence
 
     Calculates the hash value of \a key, using
     \a seed to seed the calculation.