Comment clean-up and remove invalid function prototype.

I don't think the function xtrn_access() *ever* existed, but this prototype seems to have been around forever.

src/sbbs3/sbbs.h

 /* Synchronet class (sbbs_t) definition and exported function prototypes */
-// vi: tabstop=4
-/* $Id: sbbs.h,v 1.583 2020/08/17 00:48:28 rswindell Exp $ */
 
 /****************************************************************************
  * @format.tab-size 4		(Plain Text/Source Code File Header)			*
@@ -15,21 +13,9 @@
  * See the GNU General Public License for more details: gpl.txt or			*
  * http://www.fsf.org/copyleft/gpl.html										*
  *																			*
- * Anonymous FTP access to the most recent released source is available at	*
- * ftp://vert.synchro.net, ftp://cvs.synchro.net and ftp://ftp.synchro.net	*
- *																			*
- * Anonymous CVS access to the development source and modification history	*
- * is available at cvs.synchro.net:/cvsroot/sbbs, example:					*
- * cvs -d :pserver:anonymous@cvs.synchro.net:/cvsroot/sbbs login			*
- *     (just hit return, no password is necessary)							*
- * cvs -d :pserver:anonymous@cvs.synchro.net:/cvsroot/sbbs checkout src		*
- *																			*
  * For Synchronet coding style and modification guidelines, see				*
  * http://www.synchro.net/source.html										*
  *																			*
- * You are encouraged to submit any modifications (preferably in Unix diff	*
- * format) via e-mail to mods@synchro.net									*
- *																			*
  * Note: If this box doesn't appear square, then you need to fix your tabs.	*
  ****************************************************************************/
 
@@ -477,7 +463,7 @@ public:
 	char 	*text[TOTAL_TEXT];			/* Text from ctrl\text.dat */
 	char 	*text_sav[TOTAL_TEXT];		/* Text from ctrl\text.dat */
 
-	char 	dszlog[127];	/* DSZLOG enviornment variable */
+	char 	dszlog[127];	/* DSZLOG environment variable */
     int     keybuftop,keybufbot;    /* Keyboard input buffer pointers (for ungetkey) */
 	char    keybuf[KEY_BUFSIZE];    /* Keyboard input buffer */
 	size_t	keybuf_space(void);
@@ -1041,7 +1027,6 @@ public:
 				,ulong misc);
 	bool	exec_xtrn(uint xtrnnum);			/* Executes online external program */
 	bool	user_event(user_event_t);			/* Executes user event(s) */
-	char	xtrn_access(uint xnum);			/* Does useron have access to xtrn? */
 	void	moduserdat(uint xtrnnum);
 	const char* xtrn_dropdir(const xtrn_t*, char* buf, size_t);