Add .arcconfig to the repository. Useful if someone wants to use phabricator's command line tool.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@169086 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/.arcconfig b/.arcconfig
new file mode 100644
index 0000000..7f45342
--- /dev/null
+++ b/.arcconfig
@@ -0,0 +1,4 @@
+{
+  "project_id" : "clang",
+  "conduit_uri" : "http://llvm-reviews.chandlerc.com/"
+}