package/libsemanage: add patch to fix Blackfin build issue

libsemanage use the same build system than libselinux,
so it's affected by the same issue.

Fixes:
http://autobuild.buildroot.net/results/39d/39d3460e88a1316ec7dbcd0d67b7fdb992c3fc77



Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>