control of command-line usage entry in '?' menu

Instead of using a compile-time macro to suppress inclusion of the
menu entry to show UNIX command-line usage in the help menu, use a
sysconf setting instead.

Default is HIDEUSAGE=0, to include the entry for command-line usage.
Set HIDEUSAGE=1 to exclude that.  Does not affect 'nethack --usage'
if player actually has access to the command-line.

src/files.c

@@ -2577,6 +2577,9 @@ parse_config_line(char *origbuf)
         }
         sysopt.seduce = n;
         sysopt_seduce_set(sysopt.seduce);
+    } else if (in_sysconf && match_varname(buf, "HIDEUSAGE", 9)) {
+        n = !!atoi(bufp);
+        sysopt.hideusage = n;
     } else if (in_sysconf && match_varname(buf, "MAXPLAYERS", 10)) {
         n = atoi(bufp);
         /* XXX to get more than 25, need to rewrite all lock code */

src/pager.c

@@ -32,9 +32,7 @@ static void dispfile_optionfile(void);
 static void dispfile_optmenu(void);
 static void dispfile_license(void);
 static void dispfile_debughelp(void);
-#ifndef HIDE_USAGE
 static void dispfile_usagehelp(void);
-#endif
 static void hmenu_doextversion(void);
 static void hmenu_dohistory(void);
 static void hmenu_dowhatis(void);
@@ -2358,13 +2356,11 @@ dispfile_debughelp(void)
     display_file(DEBUGHELP, TRUE);
 }
 
-#ifndef HIDE_USAGE
 static void
 dispfile_usagehelp(void)
 {
     display_file(USAGEHELP, TRUE);
 }
-#endif
 
 static void
 hmenu_doextversion(void)
@@ -2423,9 +2419,7 @@ static const struct {
     { dokeylist, "Full list of keyboard commands." },
     { hmenu_doextlist, "List of extended commands." },
     { domenucontrols, "List menu control keys." },
-#ifndef HIDE_USAGE
     { dispfile_usagehelp, "Description of NetHack's command line." },
-#endif
     { dispfile_license, "The NetHack license." },
     { docontact, "Support information." },
 #ifdef PORT_HELP
@@ -2455,6 +2449,9 @@ dohelp(void)
     for (i = 0; help_menu_items[i].text; i++) {
         if (!wizard && help_menu_items[i].f == dispfile_debughelp)
             continue;
+        if (sysopt.hideusage && help_menu_items[i].f == dispfile_usagehelp)
+            continue;
+
         if (help_menu_items[i].text[0] == '%') {
             Sprintf(helpbuf, help_menu_items[i].text, PORT_ID);
         } else if (help_menu_items[i].f == dispfile_optmenu) {

src/sys.c

@@ -81,6 +81,10 @@ sys_early_init(void)
 #ifdef WIN32
     sysopt.portable_device_paths = 0;
 #endif
+
+    /* help menu */
+    sysopt.hideusage = 0;
+
     return;
 }