LU-1337 build: make configure process not break for 3.4 kernel

LU-1337 build: make configure process not break for 3.4 kernel

1. remove "ifeq ($(PATCHLEVEL),4)" from build/Makefile, Rules.in
   "ifeq ($(PATCHLEVEL),4)" is for old 2.4 kernel, it breaks
   configuration process for 3.4 kernel.
2. change the "-include" file from "include/$AUTOCONF_HDIR/autoconf.h"
   to "include/linux/kconfig.h", as kconfig.h includes autoconf.h and
   defines some macros(IS_ENABLED etc.) which is needed for some
   header files.
3. Fix a typo from "blkkdev.h" to "blkdev.h" in lustre-core.m4

Signed-off-by: Liu Xuezhao <xuezhao.liu@emc.com>
Change-Id: If1c712c194ba76a2fe46c31afad28c37f0b465c6
Reviewed-on: http://review.whamcloud.com/3396
Tested-by: Hudson
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>