Add recently-created t_auth to .gitignore.
diff --git a/.gitignore b/.gitignore
index 424b143..c98bd44 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,6 +25,7 @@
 src/t_units
 src/t_uuid
 src/t_api
+src/t_auth
 examples/.libs
 examples/Makefile
 examples/mic