patch 8.0.1516: errors for job options are not very specific

Problem:    Errors for job options are not very specific.
Solution:   Add more specific error messages.
diff --git a/src/version.c b/src/version.c
index 52479de..9e19833 100644
--- a/src/version.c
+++ b/src/version.c
@@ -772,6 +772,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1516,
+/**/
     1515,
 /**/
     1514,