[PATCH] kbuild: adjust .version updating

In order to maintain a more correct build number, updates to the
version
number should only be commited after a successful link of vmlinux, not
before (so that errors in the link process don't lead to pointless
increments).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>