QDoc: Numerous validly-formatted links fail to be created

QDoc reports a number of broken links, which have actually been written correctly.

Here are the ones I know of:

• qtbase/src/corelib/global/qglobal.cpp:
  • \l {Q_DECL_FINAL}
• qtdeclarative/src/quick/items/qquickpositioners.cpp | qquickdrag.cpp:
  • \l {Item::anchors}
  • \l {MouseArea::drag}
  • Known issue: Grouped properties don't link properly yet (QTBUG-35844)
• qtdeclarative/src/quick/doc/src/whatsnew.qdoc
  • \l {QtQuick.Window}
  • Clash with section headings? Part of a larger collection (QTBUG-35865)
• qtquickcontrols/src/controls/ToolButton.qml:
  • \l {Button}

Here are some new ones that have been brought out by new patches (which are unstaged at the time of writing):

• https://codereview.qt-project.org/#change,81350
  • qtdeclarative/src/quick/items/qquickgridview.cpp:
    • \l {add}
    • Name clash? "add" is the name of both an attached signal and a property.

• https://codereview.qt-project.org/#change,80280
  • These all worked before
  • qtbase/src/corelib/global/qlogging.cpp:
    • \l {qDebug()}
    • \l {qWarning()}
    • \l {qCritical()}
    • \l {qFatal()}
  • qtbase/src/corelib/global/qnumeric.cpp:
    • \l {qFuzzyCompare()}
  • qtbase/src/corelib/tools/qstring.cpp:
    • \l {qPrintable()}