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
