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>

package/libsemanage/0002-workaround-blackfin-issue.patch

@@ -0,0 +1,24 @@
+Do not make symbols hidden on Blackfin
+
+The libselinux logic to hide internal symbols from the DSO doesn't
+work properly on Blackfin due to the USER_LABEL_PREFIX not being
+handled properly. A real fix is not that simple, so this patch simply
+disables the internal symbol hiding mechanism. This means that those
+symbols are visible in the final DSO, which is not a problem for
+proper execution, it just isn't as clean.
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+
+Index: b/src/dso.h
+===================================================================
+--- a/src/dso.h
++++ b/src/dso.h
+@@ -1,7 +1,7 @@
+ #ifndef _SELINUX_DSO_H
+ #define _SELINUX_DSO_H	1
+ 
+-#ifdef SHARED
++#if defined(SHARED) && !defined(__bfin__)
+ # define hidden __attribute__ ((visibility ("hidden")))
+ # define hidden_proto(fct) __hidden_proto (fct, fct##_internal)
+ # define __hidden_proto(fct, internal)	\