[AUDIT] do not panic on exclude messages in audit_log_pid_context()

If we fail to get an ab in audit_log_pid_context this may be due to an exclude
rule rather than a memory allocation failure.  If it was due to a memory
allocation failue we would have already paniced and no need to do it again.

Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 6e5de76..aaaca8a 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -948,7 +948,7 @@
 
 	ab = audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID);
 	if (!ab)
-		return 1;
+		return rc;
 
 	audit_log_format(ab, "opid=%d oauid=%d ouid=%d oses=%d", pid, auid,
 			 uid, sessionid);