signals: add set_restore_sigmask

This adds the set_restore_sigmask() inline in <linux/thread_info.h> and
replaces every set_thread_flag(TIF_RESTORE_SIGMASK) with a call to it.  No
change, but abstracts the details of the flag protocol from all the calls.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/select.c b/fs/select.c
index 00f58c5..32ce2b3 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -498,7 +498,7 @@
 		if (sigmask) {
 			memcpy(&current->saved_sigmask, &sigsaved,
 					sizeof(sigsaved));
-			set_thread_flag(TIF_RESTORE_SIGMASK);
+			set_restore_sigmask();
 		}
 	} else if (sigmask)
 		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
@@ -805,7 +805,7 @@
 		if (sigmask) {
 			memcpy(&current->saved_sigmask, &sigsaved,
 					sizeof(sigsaved));
-			set_thread_flag(TIF_RESTORE_SIGMASK);
+			set_restore_sigmask();
 		}
 		ret = -ERESTARTNOHAND;
 	} else if (sigmask)