Doc: Add \relates command for documented global functions/macros

Global functions need an associated header file/class/namespace to make
the documentation visible.

Remove QDoc comment tag (/*!) for an internal function.

Pick-to: 6.3
Task-number: QTBUG-99578
Change-Id: Id390d433d7e081fc90fa57a02097b6c37fa13bee
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

src/corelib/global/qnumeric.cpp

@@ -256,6 +256,7 @@ Q_CORE_EXPORT quint64 qFloatDistance(double a, double b)
 
 /*!
     \fn template<typename T> bool qAddOverflow(T v1, T v2, T *result)
+    \relates <QtGlobal>
     \since 6.1
 
     Adds two values \a v1 and \a v2, of a numeric type \c T and records the
@@ -287,6 +288,7 @@ Q_CORE_EXPORT quint64 qFloatDistance(double a, double b)
 
 /*!
     \fn template<typename T> bool qSubOverflow(T v1, T v2, T *result)
+    \relates <QtGlobal>
     \since 6.1
 
     Subtracts \a v2 from \a v1 and records the resulting value in \a result. If
@@ -318,6 +320,7 @@ Q_CORE_EXPORT quint64 qFloatDistance(double a, double b)
 
 /*!
     \fn template<typename T> bool qMulOverflow(T v1, T v2, T *result)
+    \relates <QtGlobal>
     \since 6.1
 
     Multiplies \a v1 and \a v2, and records the resulting value in \a result. If

src/corelib/kernel/qmetatype.cpp

@@ -2657,7 +2657,7 @@ static inline int qMetaTypeTypeImpl(const char *typeName, int length)
 */
 
 /*!
-    \a internal
+    \internal
 
     Similar to QMetaType::type(); the only difference is that this function
     doesn't attempt to normalize the type name (i.e., the lookup will fail

src/testlib/qtestcase.qdoc

@@ -163,6 +163,7 @@
 
 /*!
    \macro QVERIFY_THROWS_EXCEPTION(exceptiontype, ...)
+   \relates QTest
    \since 6.3
 
    The QVERIFY_THROWS_EXCEPTION macro executes the expression given in the variadic

src/widgets/styles/qdrawutil.cpp

@@ -799,6 +799,7 @@ void qDrawWinButton(QPainter *p, const QRect &r,
 /*!
     \fn void qDrawWinPanel(QPainter *painter, const QRect &rect, const QPalette &palette,
              bool sunken, const QBrush *fill)
+    \relates <qdrawutil.h>
     \overload
 
     Draws the Windows-style panel at the rectangle specified by \a rect using
@@ -895,6 +896,7 @@ void qDrawPlainRect(QPainter *p, const QRect &r, const QColor &c,
 typedef QVarLengthArray<QPainter::PixmapFragment, 16> QPixmapFragmentsArray;
 
 /*!
+    \relates <qdrawutil.h>
     \since 4.6
 
     Draws the indicated \a sourceRect rectangle from the given \a pixmap into

src/widgets/widgets/qeffects.cpp

@@ -553,7 +553,7 @@ void QRollEffect::scroll()
     }
 }
 
-/*!
+/*
     Scroll widget \a w in \a time ms. \a orient may be 1 (vertical), 2
     (horizontal) or 3 (diagonal).
 */
@@ -576,7 +576,7 @@ void qScrollEffect(QWidget* w, QEffects::DirFlags orient, int time)
     q_roll->run(time);
 }
 
-/*!
+/*
     Fade in widget \a w in \a time ms.
 */
 void qFadeEffect(QWidget* w, int time)