Minijail: add logging for seccomp filter failures.

BUG=chromium-os:33361
TEST=unit tests
TEST=security_Minijail0, security_Minijail_seccomp, platform_CrosDisksArchive

Change-Id: I16cdb8fbcf1cb13f2dee5521f97fb8d0bdbdf93b
Reviewed-on: https://gerrit.chromium.org/gerrit/29053
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Tested-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Commit-Ready: Jorge Lucangeli Obes <jorgelo@chromium.org>
diff --git a/libminijail.h b/libminijail.h
index 13f9ab4..d83dc21 100644
--- a/libminijail.h
+++ b/libminijail.h
@@ -46,6 +46,7 @@
 void minijail_no_new_privs(struct minijail *j);
 void minijail_use_seccomp_filter(struct minijail *j);
 void minijail_parse_seccomp_filters(struct minijail *j, const char *path);
+void minijail_log_seccomp_filter_failures(struct minijail *j);
 void minijail_use_caps(struct minijail *j, uint64_t capmask);
 void minijail_namespace_vfs(struct minijail *j);
 /* Implies namespace_vfs and remount_readonly.