new helpers: {clear,test,test_and_clear}_restore_sigmask()

helpers parallel to set_restore_sigmask(), used in the next commits

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index eee7294..ed27970 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -127,6 +127,18 @@
 	set_thread_flag(TIF_RESTORE_SIGMASK);
 	set_thread_flag(TIF_SIGPENDING);
 }
+static inline void clear_restore_sigmask(void)
+{
+	clear_thread_flag(TIF_RESTORE_SIGMASK);
+}
+static inline bool test_restore_sigmask(void)
+{
+	return test_thread_flag(TIF_RESTORE_SIGMASK);
+}
+static inline bool test_and_clear_restore_sigmask(void)
+{
+	return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
+}
 #endif	/* TIF_RESTORE_SIGMASK && !HAVE_SET_RESTORE_SIGMASK */
 
 #ifndef HAVE_SET_RESTORE_SIGMASK