patch 8.0.1712: terminal scrollback is not limited

Problem:    Terminal scrollback is not limited.
Solution:   Add the 'terminalscroll' option.
diff --git a/src/version.c b/src/version.c
index 255e24b..41b9721 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1712,
+/**/
     1711,
 /**/
     1710,