Correctly apply miter limits when stroking lines

The PDF generator was in many cases not correctly
applying miter limits to the generated strokes leading
to drawing artifacts for very sharp edges.

Task-number: QTBUG-37903
Change-Id: Ie93b0f4a56775729105a375ba3bcdb5b58993433
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

src/gui/painting/qpdf.cpp

@@ -1347,6 +1347,8 @@ void QPdfEngine::setPen()
     int pdfJoinStyle = 0;
     switch(d->pen.joinStyle()) {
     case Qt::MiterJoin:
+    case Qt::SvgMiterJoin:
+        *d->currentPage << d->pen.miterLimit() << "M ";
         pdfJoinStyle = 0;
         break;
     case Qt::BevelJoin: