patch 9.0.0751: 'scrolloff' does not work well with 'smoothscroll'

Problem:    'scrolloff' does not work well with 'smoothscroll'.
Solution:   Make positioning the cursor a bit better.  Rename functions.
diff --git a/src/misc2.c b/src/misc2.c
index 5d36cc1..84c5f43 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -150,7 +150,7 @@
 
 	    if ((addspaces || finetune) && !VIsual_active)
 	    {
-		curwin->w_curswant = linetabsize(line) + one_more;
+		curwin->w_curswant = linetabsize_str(line) + one_more;
 		if (curwin->w_curswant > 0)
 		    --curwin->w_curswant;
 	    }
@@ -166,7 +166,7 @@
 		&& wcol >= (colnr_T)width
 		&& width > 0)
 	{
-	    csize = linetabsize(line);
+	    csize = linetabsize_str(line);
 	    if (csize > 0)
 		csize--;