kconfig: simplification of scripts/extract-ikconfig

I've rewritten the extract-ikconfig script to extract the kernel
configuration from a kernel compiled with CONFIG_IKCONFIG. The main
motivation for the rewrite was to remove the dependency on the
external C program binoffset.c, which is compiled on the initial run.

The binoffset executable is invoked with a relative path, which means
that the old script can only be run from the top of the kernel tree,
and only when you have write permission in the scripts directory.

The new script uses tr/grep/tail/zcat only, and can be invoked from
anywhere. The binoffset.c program has been removed. This script
requires GNU grep 2.5 (released 2002-03-13) or higher, because the -o
option was introduced in that version.

Signed-off-by: Dick Streefland <dick@streefland.net>
LKML-Reference: <20091006203540.GA14634@streefland.net>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>