kconfig: fork mconf source from olibc

Added from commit 424a2e4 of https://github.com/olibc/kconfig
with the following commit reverted

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commit e9eb3dd3b239ea10ed34cc8566ebb5bb5b37f8d0
Author: Kito Cheng <kito@0xlab.org>
Date:   Tue Jun 11 22:56:50 2013 +0800

    Output boolean value '=true' instead of '=y'
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kconfig: fix naming from olibc to F9 microkernel
mk: add kconfig support

new makefile target:
  1. config: parse Kconfig and introduce config menu
  2. distclean: clean project, then clean config files
kconfig: naming tweaks
variable name tweaks
rename external
kconfig: rename environment variables
kconfig: add CONFIG_ head back
kconfig: generate c header for kconfig

1. Generate autoconf in the end of mconf
2. Generate header file only. Remove .config.cmd, auto.conf
   and tristate.conf from generating list.
3. Change the path of autoconf.h to include/
kconfig: transparent integration with current build system
introduce Kconfig style configuration for build system

Fixes #14
mk: attempt to interpret each configuration regardless of its form

Revert commit f321695a8ed6573679f79bfe751668034f900f0b
add Viller Hsiao in developer list
mk: prevent autoconfig.h from being absent