util: Add the scons configuration cache to .gitignore for util/tlm.

Change-Id: Ife31e1bbf862d10bbe8e2c0fa36c8c168cfafa84
Reviewed-on: https://gem5-review.googlesource.com/c/14656
Reviewed-by: Matthias Jung <jungma@eit.uni-kl.de>
Maintainer: Gabe Black <gabeblack@google.com>
diff --git a/util/tlm/.gitignore b/util/tlm/.gitignore
index 5761abc..4ab8976 100644
--- a/util/tlm/.gitignore
+++ b/util/tlm/.gitignore
@@ -1 +1,2 @@
 *.o
+.sconsign.dblite