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/README.TXT b/libc/kernel/README.TXT
index 9ff97d6..1ca3350e 100644
--- a/libc/kernel/README.TXT
+++ b/libc/kernel/README.TXT
@@ -17,26 +17,27 @@
 
 the generation process works as follows:
 
-  * 'bionic/kernel/original/'
+  * 'external/kernel-headers/original/'
     contains a set of kernel headers as normally found in the 'include'
     directory of a normal Linux kernel source tree. note that this should
     only contain the files that are really needed by Android (use
     'find_headers.py' to find these automatically).
 
-  * 'bionic/kernel/common'
+  * 'bionic/libc/kernel/common'
     contains the non-arch-specific clean headers and directories
     (e.g. linux, asm-generic and mtd)
 
-  *'bionic/kernel/arch-arm/'
+  * 'bionic/libc/kernel/arch-arm/'
     contains the ARM-specific directory tree of clean headers.
 
-  * 'bionic/kernel/arch-arm/asm'
+  * 'bionic/libc/kernel/arch-arm/asm'
     contains the real ARM-specific headers
 
-  * 'bionic/kernel/arch-x86'
+  * 'bionic/libc/kernel/arch-x86'
+    'bionic/libc/kernel/arch-x86/asm'
     similarly contains all headers and symlinks to be used on x86
 
-  * 'bionic/kernel/tools' contains various Python and shell scripts used
+  * 'bionic/libc/kernel/tools' contains various Python and shell scripts used
     to manage and re-generate the headers
 
 the tools you can use are: