Add bazel-toolchain repository

Going to use this to get a newer Clang with a nicer Bazel toolchain
setup.

Change-Id: Iea0cb857340d528752f6a47f1d9917a483d5452c
Signed-off-by: Brian Silverman <bsilver16834@gmail.com>
diff --git a/WORKSPACE b/WORKSPACE
index d532887..990a7d3 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -80,6 +80,11 @@
 )
 load("//debian:packages.bzl", "generate_repositories_for_debs")
 
+local_repository(
+    name = "com_grail_bazel_toolchain",
+    path = "third_party/bazel-toolchain",
+)
+
 generate_repositories_for_debs(python_debs)
 
 generate_repositories_for_debs(clang_debs)