patch 9.1.0258: half-page scrolling broke backward compatibility

Problem:  Support for 'smoothscroll' in (half-)page scrolling
          broke backward compatibility and can be made to work better.
          (after v9.1.215)
Solution: Restore the previous cursor and end-of-buffer behavior for
          half-page scrolling and improve 'smoothscroll' support.
          (Luuk van Baal)

fixes: #14338
closes: #14377

Signed-off-by: Luuk van Baal <luukvbaal@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/normal.pro b/src/proto/normal.pro
index eff08df..afa0799 100644
--- a/src/proto/normal.pro
+++ b/src/proto/normal.pro
@@ -22,6 +22,8 @@
 void do_check_scrollbind(int check);
 void check_scrollbind(linenr_T topline_diff, long leftcol_diff);
 int find_decl(char_u *ptr, int len, int locally, int thisblock, int flags_arg);
+void nv_g_home_m_cmd(cmdarg_T *cap);
+int nv_screengo(oparg_T *oap, int dir, long dist);
 void nv_scroll_line(cmdarg_T *cap);
 void scroll_redraw(int up, long count);
 void handle_tabmenu(void);