Build fixes for recent Bazel versions

We need to add the `oss-internship-2020` and `examples/hello_sapi`
directories to `.bazelignore`, so that `bazel build ...` works on a clean
working copy. This is because the Bazel builds in these directories use their
own `WORKSPACE.bazel` and this does not nest well, leading to all kinds of
hard to debug errors.

PiperOrigin-RevId: 333728800
Change-Id: Ie2e68dd39bf6f8eb21af29d8ae3ae12971b408db

.bazelignore

@@ -0,0 +1,4 @@
+# Using CMake or own WORKSPACE
+oss-internship-2020
+# Uses its own WORKSPACE
+sandboxed_api/examples/hello_sapi

sandboxed_api/examples/hello_sapi/BUILD.bazel

@@ -40,7 +40,6 @@ sapi_library(
 cc_binary(
     name = "hello",
     srcs = ["hello_main.cc"],
-    includes = ["."],  # To find the generated header
     deps = [":hello_sapi"],
 )
 
@@ -50,7 +49,6 @@ cc_binary(
 cc_binary(
     name = "hello_transacted",
     srcs = ["hello_transacted.cc"],
-    includes = ["."],  # To find the generated header
     deps = [
         ":hello_sapi",
         "@com_google_absl//absl/memory",

sandboxed_api/util/BUILD.bazel

@@ -46,6 +46,7 @@ cc_library(
     name = "statusor",
     hdrs = ["statusor.h"],
     deprecation = "Migrate to `absl::StatusOr<T>`",
+    visibility = ["//visibility:public"],
     deps = [
         "@com_google_absl//absl/base:core_headers",
         "@com_google_absl//absl/status:statusor",