remove bashisms from scripts/extract-ikconfig

unbashify-extract-ikconfig.patch

scripts/extract-ikconfig contains a lot of gratuituous bashisms,
which make it fail if /bin/sh isn't bash. This patch replaces them
with regular Bourne shell constructs.

Signed-off-by: Werner Almesberger <werner@openmoko.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com> # as file author
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>