Fixed to #include correct 32-bit headers; Refreshed libc/kernel headers

This patch fixes an issue where 64-bit hreaders are incorrectly included
in kernel headers.  For example, file "libc/kernel/arch-x86/asm/io.h"
incorreclty includes "io_64.h" (missing, BTW) instead of "io_32.h".

The reason is because CONFIG_X86_32 isn't considered pre-defined in
"kernel_default_arch_macros" for x86, and clean_header.py doesn't
look at it at all anyway (ie. __i386__ is also ignored, but it's
okay since x86 cross compiler defines it back)

Fixed 2 tools/*py, README.TXT, and refreshed libc/kernel headers

Change-Id: Iac834cc8b3548f055d3f2a214af36072dd679fe8
diff --git a/libc/kernel/arch-x86/asm/acpi.h b/libc/kernel/arch-x86/asm/acpi.h
index 255f7dc..92e6b7d 100644
--- a/libc/kernel/arch-x86/asm/acpi.h
+++ b/libc/kernel/arch-x86/asm/acpi.h
@@ -18,7 +18,7 @@
  ****************************************************************************/
 #ifndef _ASM_X86_ACPI_H
 #define _ASM_X86_ACPI_H
-#include "acpi_64.h"
+#include "acpi_32.h"
 #include <asm/processor.h>
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #endif