gitignore: Add test-driver

Add test-driver object to gitignore.

Change-Id: I0395e9a95a977831fa995b4bd0bf400901b46d70
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/.gitignore b/.gitignore
index 134df69..0e8d05d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -39,7 +39,7 @@
 install-sh
 ltmain.sh
 missing
-
+test-driver
 
 # Custom generated files