Fix memory leak in TGraph2DPainter::PaintContour
Fix memory leak in TGraph2DPainter::PaintContour

Appears when TGrpah2D drawn with "cont5" option
root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,karies/root,karies/root,olifre/root,karies/root,root-mirror/root,karies/root,olifre/root,olifre/root,olifre/root,root-mirror/root,karies/root,karies/root,olifre/root,root-mirror/root,olifre/root,karies/root,karies/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,karies/root,olifre/root,karies/root,olifre/root