patch 8.0.1758: open_line() returns TRUE/FALSE for success/failure

Problem:    open_line() returns TRUE/FALSE for success/failure.
Solution:   Return OK or FAIL.
diff --git a/src/version.c b/src/version.c
index f0cb304..dfd82f9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1758,
+/**/
     1757,
 /**/
     1756,