Add CI config to test on RBE. (#111)

* Add CI config to test on RBE.

* Skip tests that are failing on RBE.

Also use latest release of bazel-toolchains.

.bazelci/presubmit.yml

@@ -23,4 +23,21 @@ platforms:
     - "-@examples//ffi/rust_calling_c:matrix_dylib_test"
     - "-@examples//ffi/rust_calling_c:matrix_dynamically_linked"
     build_targets: *targets
-    test_targets: *targets
+    test_targets: *targets
+  rbe_ubuntu1604:
+    test_targets:
+    - "--"
+    - "//test/..."
+    - "@examples//..."
+    - "-//test/conflicting_deps:conflicting_deps_test"
+    - "-@examples//hello_runfiles:hello_runfiles_test"
+    - "-@examples//ffi/c_calling_rust:main"
+    - "-@examples//ffi/rust_calling_c:matrix_dylib_test"
+    - "-@examples//ffi/rust_calling_c:matrix_test"
+    - "-@examples//fibonacci:fibonacci_doc_test"
+    - "-@examples//fibonacci:fibonacci_test"
+    - "-@examples//hello_lib:greeting_test"
+    - "-@examples//hello_lib:hello_lib_doc_test"
+    - "-@examples//hello_lib:hello_lib_test"
+    - "-@examples//hello_world:hello_world_doc_test"
+    - "-@examples//hello_out_dir:hello_out_dir_test"

WORKSPACE

@@ -5,6 +5,7 @@ load(
     "git_repository",
     "new_git_repository",
 )
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 local_repository(
     name = "examples",
@@ -48,3 +49,13 @@ git_repository(
 load("@io_bazel_skydoc//skylark:skylark.bzl", "skydoc_repositories")
 
 skydoc_repositories()
+
+http_archive(
+    name = "bazel_toolchains",
+    sha256 = "c3b08805602cd1d2b67ebe96407c1e8c6ed3d4ce55236ae2efe2f1948f38168d",
+    strip_prefix = "bazel-toolchains-5124557861ebf4c0b67f98180bff1f8551e0b421",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/archive/5124557861ebf4c0b67f98180bff1f8551e0b421.tar.gz",
+        "https://github.com/bazelbuild/bazel-toolchains/archive/5124557861ebf4c0b67f98180bff1f8551e0b421.tar.gz",
+    ],
+)