Expand dot gitignore

Add cscope and vim swap files

Bug: 190219048
Test: vim
Tag: #refactor
Change-Id: Ib91792f9a60e3965f6916c891d349d28bf08e276
diff --git a/.gitignore b/.gitignore
index 5acc85a..d26e74c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,6 @@
 target/
 Cargo.lock
 tags
+cscope.out
+cscope.files
+*.sw?