package/ipmiutil: really disable lanplus

Fixes:
http://autobuild.buildroot.org/results/04a/04a1c48d484debd7894fd32997ed50d3a0110b93/



Due to weird constructs in the Makefiles, lanplus is always built, even
when explicitly disabled with --disable-lanplus .

So, add a patch to enforce disabling lanplus. We're doing an at-minima
patch just for the upcoming Buildroot release, and to avoid diverging
too far from upstream...

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Peter Korsgaard <jacmet@uclibc.org>
Cc: Romain Naour <romain.naour@openwide.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>