patch 8.2.0482: channel and sandbox code not sufficiently tested

Problem:    Channel and sandbox code not sufficiently tested.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5855)
diff --git a/src/option.h b/src/option.h
index 47eb151..52166cf 100644
--- a/src/option.h
+++ b/src/option.h
@@ -403,7 +403,7 @@
 EXTERN char_u	*p_bo;		// 'belloff'
 EXTERN unsigned	bo_flags;
 
-// values for the 'beepon' option
+// values for the 'belloff' option
 #define BO_ALL		0x0001
 #define BO_BS		0x0002
 #define BO_CRSR		0x0004