patch 9.0.1000: with 'smoothscroll' skipcol may be reset unnecessarily

Problem:    With 'smoothscroll' skipcol may be reset unnecessarily.
Solution:   Check the line does actually fit in the window.

src/move.c

@@ -1909,7 +1909,11 @@ adjust_skipcol(void)
     int	    scrolled = FALSE;
 
     validate_cheight();
-    if (curwin->w_cline_height == curwin->w_height)
+    if (curwin->w_cline_height == curwin->w_height
+	    // w_cline_height may be capped at w_height, check there aren't
+	    // actually more lines.
+	    && plines_win(curwin, curwin->w_cursor.lnum, FALSE)
+							   <= curwin->w_height)
     {
 	// the line just fits in the window, don't scroll
 	reset_skipcol();

src/testdir/dumps/Test_smooth_long_9.dump

@@ -1,6 +1,6 @@
-|<+0#4040ff13#ffffff0@2|o+0#0000000&|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o
+|<+0#4040ff13#ffffff0@2|t+0#0000000&|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t
-|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o
+|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o
-|f| |t|e|x|t| |w|i>t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e
+|t|s| |o|f| |t|e|x>t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o
+|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e
 |x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w
-|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |w|i|t|h| 
+|:|s|e|t| |s|c|r|o|l@1|o| @9|3|,|1|3|0| @8|6@1|%| 
-@22|3|,|1|7|0| @8|6@1|%| 

src/testdir/test_scroll_opt.vim

@@ -481,6 +481,13 @@ func Test_smoothscroll_cursor_scrolloff()
   exe "normal 20h"
   call s:check_col_calc(1, 4, 61)
 
+  " cursor on last line, "gk" should not cause a scroll
+  set scrolloff=0
+  normal G0
+  call s:check_col_calc(1, 7, 1)
+  normal gk
+  call s:check_col_calc(1, 6, 101)
+
   bwipe!
 endfunc
 

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1000,
 /**/
     999,
 /**/