gitignore: add gtp-link, gtp-tunnel

Change-Id: I9f9c9f64d96e25d99c5631ec40c1439f76678905
diff --git a/.gitignore b/.gitignore
index 738b3c4..bf5732d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -34,3 +34,6 @@
 debian/libgtpnl0
 
 contrib/libgtpnl.spec
+
+tools/gtp-link
+tools/gtp-tunnel