scripts: dummy-tools, add pahole

CONFIG_PAHOLE_VERSION is a part of a config since the commit below. And
when multiple people update the config, this value constantly changes.
Even if they use dummy scripts.

To fix this, add a pahole dummy script returning v99.99. (This is
translated into 9999 later in the process.)

Thereafter, this script can be invoked easily for example as:
make PAHOLE=scripts/dummy-tools/pahole oldconfig

Fixes: 613fe1692377 (kbuild: Add CONFIG_PAHOLE_VERSION)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>