Ignore ctags index file.

R=szager@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/14207002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@193826 0039d316-1c4b-4281-b951-d872f2087c98

.gitignore

@@ -24,6 +24,14 @@
 /git_bin
 /svn_bin
 
+# Ignore ctags/cscope index files
+/TAGS
+/cscope.files
+/cscope.in.out
+/cscope.out
+/cscope.po.out
+/tags
+
 # Ignore unittest related files.
 /testing_support/_rietveld
 /tests/git-svn-submodule/