patch 8.0.1599: no error message when gdb does not support debugger

Problem:    No error message when gdb does not support the terminal debugger.
Solution:   Check for the response to open the Machine Interface.

src/version.c

@@ -766,6 +766,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1599,
 /**/
     1598,
 /**/