shell: split read builtin from ash

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

shell/math.c

@@ -1,20 +1,17 @@
 /*
  * arithmetic code ripped out of ash shell for code sharing
  *
+ * This code is derived from software contributed to Berkeley by
+ * Kenneth Almquist.
+ *
+ * Original BSD copyright notice is retained at the end of this file.
+ *
  * Copyright (c) 1989, 1991, 1993, 1994
  *      The Regents of the University of California.  All rights reserved.
  *
  * Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
  * was re-ported from NetBSD and debianized.
  *
- * This code is derived from software contributed to Berkeley by
- * Kenneth Almquist.
- *
- * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
- *
- * Original BSD copyright notice is retained at the end of this file.
- */
-/*
  * rewrite arith.y to micro stack based cryptic algorithm by
  * Copyright (c) 2001 Aaron Lehmann <aaronl@vitelus.com>
  *
@@ -25,6 +22,8 @@
  * used in busybox and size optimizations,
  * rewrote arith (see notes to this), added locale support,
  * rewrote dynamic variables.
+ *
+ * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  */
 #include "libbb.h"
 #include "math.h"