Fix docs of qAbs to have the correct function signature.

Change-Id: I984032dc58387ae8f28318beeb053af28ccc8885
Reviewed-by: Casper van Donderen <casper.vandonderen@nokia.com>

src/corelib/global/qglobal.cpp

@@ -740,7 +740,7 @@ Q_CORE_EXPORT void *qMemSet(void *dest, int c, size_t n);
     \sa quint64, qlonglong
 */
 
-/*! \fn const T &qAbs(const T &value)
+/*! \fn T qAbs(const T &value)
     \relates <QtGlobal>
 
     Compares \a value to the 0 of type T and returns the absolute