patch 8.2.2500: build fails without the GUI feature

Problem:    Build fails without the GUI feature.
Solution:   Add #ifdef.

src/main.c

@@ -1979,7 +1979,9 @@ command_line_scan(mparm_T *parmp)
 		{
 		    Columns = 80;	// need to init Columns
 		    info_message = TRUE; // use mch_msg(), not mch_errmsg()
+#if defined(FEAT_GUI) && !defined(ALWAYS_USE_GUI)
 		    gui.starting = FALSE; // not starting GUI, will exit
+#endif
 		    list_version();
 		    msg_putchar('\n');
 		    msg_didout = FALSE;

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2500,
 /**/
     2499,
 /**/