patch 9.0.1367: divide by zero in zero-width window

Problem:    Divide by zero in zero-width window.
Solution:   Check the width is positive.
diff --git a/src/move.c b/src/move.c
index 921fec6..0550ef5 100644
--- a/src/move.c
+++ b/src/move.c
@@ -1734,7 +1734,7 @@
 	    col -= width1;
 	    ++row;
 	}
-	if (col > width2)
+	if (col > width2 && width2 > 0)
 	{
 	    row += col / width2;
 	    col = col % width2;