[POWERPC] Define and use TLF_RESTORE_SIGMASK

Replace TIF_RESTORE_SIGMASK with TLF_RESTORE_SIGMASK and define
our own set_restore_sigmask() function.  This saves the costly
SMP-safe set_bit operation, which we do not need for the sigmask
flag since TIF_SIGPENDING always has to be set too.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index ad69434..4ae16d1 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -243,7 +243,7 @@
 
  	current->state = TASK_INTERRUPTIBLE;
  	schedule();
- 	set_thread_flag(TIF_RESTORE_SIGMASK);
+	set_restore_sigmask();
  	return -ERESTARTNOHAND;
 }