Add libfuzzer test for QTextLayout::beginLayout()

Task-number: QTBUG-77819
Change-Id: I34e9cbaa615896222bcf947012cfed9f6c3186c7
Reviewed-by: Rainer Keller <Rainer.Keller@qt.io>

tests/libfuzzer/gui/text/qtextlayout/beginLayout/beginLayout.pro

@@ -0,0 +1,3 @@
+QT += widgets
+SOURCES += main.cpp
+LIBS += -fsanitize=fuzzer

tests/libfuzzer/gui/text/qtextlayout/beginLayout/main.cpp

@@ -0,0 +1,36 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QTextLayout>
+
+extern "C" int LLVMFuzzerTestOneInput(const char *Data, size_t Size) {
+    QTextLayout tl(QByteArray::fromRawData(Data, Size));
+    tl.beginLayout();
+    tl.endLayout();
+    return 0;
+}