Fix warning in TQRootCanvas
Fix warning in TQRootCanvas

TQRootCanvas.cxx:759:54: warning:
    declaration of ‘y’ shadows a member of 'this'

root-mirror/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,karies/root,olifre/root,karies/root,olifre/root,karies/root,olifre/root,olifre/root,karies/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,karies/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,root-mirror/root,karies/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,root-mirror/root,karies/root