Revert "tests: disable broken tests/bgp_mp_attr_test.c"

This reverts commit d78e2b8b562f8496aaf2977f7371415b71e82433. Next 2
commits fix it.
diff --git a/tests/bgp_mp_attr_test.c b/tests/bgp_mp_attr_test.c
index cf0b2b1..9cbe9f2 100644
--- a/tests/bgp_mp_attr_test.c
+++ b/tests/bgp_mp_attr_test.c
@@ -1,8 +1,3 @@
-/* this testcase is currently broken
- * -- 2012-05-01 David Lamparter <equinox@diac24.net>
- */
-int main() { return 0; }
-
 #include <zebra.h>
 
 #include "vty.h"
@@ -29,7 +24,6 @@
 struct zebra_privs_t *bgpd_privs = NULL;
 struct thread_master *master = NULL;
 
-#if 0
 static int failed = 0;
 static int tty = 0;
 
@@ -539,4 +533,3 @@
   printf ("failures: %d\n", failed);
   return failed;
 }
-#endif /* #if 0 */