Rename FH_BAD to FH_NADA throughout.

* devices.h (FH_ERROR): New value.
(iscons_dev): Extend to detect all the console device types.
* devices.in: Set aside storage for FH_ERROR.
* dtable.cc (dtable::init_std_file_from_handle): Use iscons_dev to detect when
device is a console.
(fh_alloc): Pass device to console constructor.
(build_fh_pc): Short circuit when we detect that the constructor saw an error.
* fhandler.h (fhandler_console::fhandler_console): Accept fh_devices parameter.
(get_tty_stuff): Change to void.
* fhandler_console (fhandler_console::set_unit): Set device to FH_ERROR on
attempt to access anything other than the current console.
(fhandler_console::get_tty_stuff): Change to void return.
(fhandler_console::open): Return EPERM on FH_ERROR device type.
(fhandler_console::fhandler_console): Set the device type appropriately before
calling get_tty_stuff and rely on that function to reset it if necessary.

winsup/cygwin/fhandler_proc.cc

@@ -68,7 +68,7 @@ static const virt_tab_t proc_tab[] = {
   { _VN ("sysvipc"),	 FH_PROCSYSVIPC,	virt_directory,	NULL },
   { _VN ("uptime"),	 FH_PROC,	virt_file,	format_proc_uptime },
   { _VN ("version"),	 FH_PROC,	virt_file,	format_proc_version },
-  { NULL, 0,	   	 FH_BAD,	virt_none,	NULL }
+  { NULL, 0,	   	 FH_NADA,	virt_none,	NULL }
 };
 
 #define PROC_DIR_COUNT 4
@@ -96,7 +96,7 @@ virt_tab_t *
 virt_tab_search (const char *path, bool prefix, const virt_tab_t *table,
 		 size_t nelem)
 {
-  virt_tab_t key = { path, 0, FH_BAD, virt_none, NULL };
+  virt_tab_t key = { path, 0, FH_NADA, virt_none, NULL };
   virt_tab_t *entry = (virt_tab_t *) bsearch (&key, table, nelem,
 					      sizeof (virt_tab_t),
 					      proc_tab_cmp);
@@ -141,7 +141,7 @@ fhandler_proc::get_proc_fhandler (const char *path)
 
   if (has_subdir)
     /* The user is trying to access a non-existent subdirectory of /proc. */
-    return FH_BAD;
+    return FH_NADA;
   else
     /* Return FH_PROC so that we can return EROFS if the user is trying to
        create a file. */