patch 8.0.1715: terminal buffer can be 1 more than 'terminalscroll' lines

Problem:    Terminal buffer can be 1 more than 'terminalscroll' lines.
Solution:   Change > to >=.
diff --git a/src/terminal.c b/src/terminal.c
index be594c4..93b6f92 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -2518,7 +2518,7 @@
 
     /* If the number of lines that are stored goes over 'termscrollback' then
      * delete the first 10%. */
-    if (term->tl_scrollback.ga_len > p_tlsl)
+    if (term->tl_scrollback.ga_len >= p_tlsl)
     {
 	int	todo = p_tlsl / 10;
 	int	i;