gitignore: Add missing /test/timer binary

This was never added when the test was made

Change-Id: I15655cdf131d8baef02c3856c53c79e014b9cf24
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/.gitignore b/.gitignore
index 2a35321..b6813f2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -60,6 +60,7 @@
 /test/message_native_types
 /test/message_read
 /test/message_types
+/test/timer
 /test/utility_tuple_to_array
 /test/utility_type_traits
 /test/vtable_vtable