Move SUSv2 obsolete feature disabling to debug menu, invert meaning of

symbol (switched on to remove now: test your apps to make sure they _don't_
do this, because as some point we should just yank it), fixup head/tail/fold.

Also tweak "make allyesconfig" so anything starting with CONFIG_DEBUG gets
left switched off.  Possibly other things we want to put in the debug menu?

coreutils/head.c

@@ -4,20 +4,7 @@
  *
  * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
 /* BB_AUDIT SUSv3 compliant */
@@ -56,7 +43,7 @@ int head_main(int argc, char **argv)
 	int c;
 	int retval = EXIT_SUCCESS;
 
-#if defined CONFIG_FEATURE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
+#if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
 	/* Allow legacy syntax of an initial numeric option without -n. */
 	if ((argc > 1) && (argv[1][0] == '-')
 		/* && (isdigit)(argv[1][1]) */
@@ -85,7 +72,7 @@ int head_main(int argc, char **argv)
 #endif
 			case 'n':
 				p = optarg;
-#if defined CONFIG_FEATURE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
+#if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
 			GET_COUNT:
 #endif
 				count = bb_xgetularg10(p);