Ignore cscope index

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/.gitignore b/.gitignore
index 789f57e..5fb0bde 100644
--- a/.gitignore
+++ b/.gitignore
@@ -40,4 +40,5 @@
 /GSYMS
 /GTAGS
 /TAGS
+/cscope*.out
 /tags