patch 9.0.1428: cursor in wrong position when leaving insert mode

Problem:    Cursor in wrong position when leaving insert mode.
Solution:   Update the w_valid flags.  Position the cursor also when not
            redrawing. (closes #12137)
diff --git a/src/edit.c b/src/edit.c
index 212efae..84b6eef 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -3688,6 +3688,7 @@
 	else
 	{
 	    --curwin->w_cursor.col;
+	    curwin->w_valid &= ~(VALID_WCOL|VALID_VIRTCOL);
 	    // Correct cursor for multi-byte character.
 	    if (has_mbyte)
 		mb_adjust_cursor();