Incorporate patches from Dimitre T. so that the source will compile w…

…ith Qt 5.15.x.

src/GuiQt/ChartTwoOverlayViewController.cxx

@@ -31,6 +31,7 @@
 #include <QMenu>
 #include <QMessageBox>
 #include <QPainter>
+#include <QPainterPath>
 #include <QSpinBox>
 #include <QToolButton>
 #include <QWidgetAction>

src/Qwt/qwt_null_paintdevice.cpp

@@ -10,6 +10,7 @@
 #include "qwt_null_paintdevice.h"
 #include <qpaintengine.h>
 #include <qpixmap.h>
+#include <QPainterPath>
 
 class QwtNullPaintDevice::PrivateData
 {

src/Qwt/qwt_painter.cpp

@@ -27,6 +27,7 @@
 #include <qpaintengine.h>
 #include <qapplication.h>
 #include <qdesktopwidget.h>
+#include <QPainterPath>
 
 #if QT_VERSION >= 0x050000
 #include <qwindow.h>

src/Qwt/qwt_painter_command.h

@@ -15,6 +15,7 @@
 #include <qpixmap.h>
 #include <qimage.h>
 #include <qpolygon.h>
+#include <QPainterPath>
 
 class QPainterPath;
 

src/Qwt/qwt_plot_panner.cpp

@@ -14,6 +14,7 @@
 #include <qbitmap.h>
 #include <qstyle.h>
 #include <qstyleoption.h>
+#include <QPainterPath>
 
 static QBitmap qwtBorderMask( const QWidget *canvas, const QSize &size )
 {

src/Qwt/qwt_plot_renderer.cpp

@@ -23,6 +23,7 @@
 #if QT_VERSION >= 0x050000
 #include <QtPrintSupport/QPrinter>
 #include <QtPrintSupport/QPrintDialog>
+#include <QPainterPath>
 #else // QT_VERSION
 #include <qprinter.h>
 #include <qprintdialog.h>

src/Qwt/qwt_widget_overlay.cpp

@@ -13,6 +13,7 @@
 #include <qpaintengine.h>
 #include <qimage.h>
 #include <qevent.h>
+#include <QPainterPath>
 
 static QImage::Format qwtMaskImageFormat()
 {