GnomeScreensaver: aspect ratio is for entire virtual screen, not just one monitor

modes/Spin.cc

@@ -29,7 +29,8 @@ bool Spin::configure (GnomeScreensaver & gs)
 {
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
-    gluPerspective(60.0, gs.getAspectRatio(), 0.01, 1000.0);
+    gluPerspective(60.0, gs.getAspectRatio() / gs.getNumMonitors(),
+            0.01, 1000.0);
 
     glMatrixMode(GL_MODELVIEW);
     glLoadIdentity();