TBR: Add gitignore.

PresubmitTest: none
Change-Id: I4e140d0c5ca2f37fe1100b80f81f78fd2bace420
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4209dc0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/.jiri