SegmentVisitor: fix crash if vertexCount is 0

Change-Id: I97a981f65cad1e2f08f90b72adfbd4945cdc2f8b
Reviewed-by: Mike Krus <mike.krus@kdab.com>
(cherry picked from commit 26577c869f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 5a5b8438f4)

src/render/backend/segmentsvisitor.cpp

@@ -150,6 +150,9 @@ void traverseSegmentStrip(Vertex *vertices,
 {
     uint i = 0;
 
+    if (vertexInfo.count < 1)
+        return;
+
     const uint verticesStride = vertexInfo.byteStride / sizeof(Vertex);
     const uint maxVerticesDataSize = qMin(vertexInfo.dataSize, 3U);