cred: export get_task_cred().

There is no reason that modules should not be able
to use this, and NFS will need it when converted to
use 'struct cred'.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

kernel/cred.c

@@ -200,6 +200,7 @@ const struct cred *get_task_cred(struct task_struct *task)
 	rcu_read_unlock();
 	return cred;
 }
+EXPORT_SYMBOL(get_task_cred);
 
 /*
  * Allocate blank credentials, such that the credentials can be filled in at a