Update bazel toolchains pin and add toolchain config target (bazelbui…

…ld#710)

New target will be used by BuildKite CI rbe_ubuntu1604 config

WORKSPACE

@@ -152,14 +152,22 @@ format_repositories()
 
 http_archive(
     name = "bazel_toolchains",
-    sha256 = "109a99384f9d08f9e75136d218ebaebc68cc810c56897aea2224c57932052d30",
-    strip_prefix = "bazel-toolchains-94d31935a2c94fe7e7c7379a0f3393e181928ff7",
+    sha256 = "4b1468b254a572dbe134cc1fd7c6eab1618a72acd339749ea343bd8f55c3b7eb",
+    strip_prefix = "bazel-toolchains-d665ccfa3e9c90fa789671bf4ef5f7c19c5715c4",
     urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/archive/94d31935a2c94fe7e7c7379a0f3393e181928ff7.tar.gz",
-        "https://github.com/bazelbuild/bazel-toolchains/archive/94d31935a2c94fe7e7c7379a0f3393e181928ff7.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/archive/d665ccfa3e9c90fa789671bf4ef5f7c19c5715c4.tar.gz",
+        "https://github.com/bazelbuild/bazel-toolchains/archive/d665ccfa3e9c90fa789671bf4ef5f7c19c5715c4.tar.gz",
     ],
 )
 
+load("@bazel_toolchains//rules:rbe_repo.bzl", "rbe_autoconfig")
+
+# Creates toolchain configuration for remote execution with BuildKite CI
+# for rbe_ubuntu1604
+rbe_autoconfig(
+    name = "buildkite_config",
+)
+
 git_repository(
     name = "bazel_skylib",
     remote = "https://github.com/bazelbuild/bazel-skylib.git",