patch 9.0.1380: CTRL-X on 2**64 subtracts two

Problem:    CTRL-X on 2**64 subtracts two. (James McCoy)
Solution:   Correct computation for large number. (closes #12103)
diff --git a/src/strings.c b/src/strings.c
index 22361ca..2099794 100644
--- a/src/strings.c
+++ b/src/strings.c
@@ -1188,7 +1188,7 @@
 	case 8: what |= STR2NR_OCT + STR2NR_OOCT + STR2NR_FORCE; break;
 	case 16: what |= STR2NR_HEX + STR2NR_FORCE; break;
     }
-    vim_str2nr(p, NULL, NULL, what, &n, NULL, 0, FALSE);
+    vim_str2nr(p, NULL, NULL, what, &n, NULL, 0, FALSE, NULL);
     // Text after the number is silently ignored.
     if (isneg)
 	rettv->vval.v_number = -n;