buildroot

package/ipmitool: bump version to 1.8.18

Some patches are not necessary anymore as upstream fixed the issues.

As we are not patching configure.ac anymore, there is no need to
autoreconf the package.

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>