[protobuf] Load C++,Java,Protobuf rules from Starlark

Cherry-pick of: protocolbuffers/protobuf#6432 and protocolbuffers/protobuf#6445

third_party/protobuf/3.6.1/BUILD

diff --git a/third_party/protobuf/3.6.1/BUILD b/third_party/protobuf/3.6.1/BUILD
index fc209f8..ebe8faf 100644
--- a/third_party/protobuf/3.6.1/BUILD
+++ b/third_party/protobuf/3.6.1/BUILD
@@ -1,6 +1,9 @@
 # Bazel (http://bazel.io/) BUILD file for Protobuf.
 
-load("@rules_java//java:defs.bzl", "java_import")
+load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library", "cc_test", "objc_library")
+load("@rules_java//java:defs.bzl", "java_library")
+load("@rules_proto//proto:defs.bzl", "proto_lang_toolchain", "proto_library")
+load("@rules_python//python:defs.bzl", "py_library")
 
 licenses(["notice"])
 
@@ -24,9 +27,6 @@
 load(":protobuf.bzl", "py_proto_library")
 load(":compiler_config_setting.bzl", "create_compiler_config_setting")
 
-# Needed for #9006. Hopefully a future upstream version will include this line.
-load("@rules_python//python:defs.bzl", "py_library")
-
 filegroup(
     name = "srcs",
     srcs = glob(

third_party/protobuf/3.6.1/protobuf.bzl

diff --git a/third_party/protobuf/3.6.1/protobuf.bzl b/third_party/protobuf/3.6.1/protobuf.bzl
index 24e333a..31fd92c 100644
--- a/third_party/protobuf/3.6.1/protobuf.bzl
+++ b/third_party/protobuf/3.6.1/protobuf.bzl
@@ -1,4 +1,4 @@
-# Needed for #9006. Hopefully a future upstream version will include this line.
+load("@rules_cc//cc:defs.bzl", "cc_library")
 load("@rules_python//python:defs.bzl", "py_library", "py_test")
 
 def _GetPath(ctx, path):
@@ -227,7 +227,7 @@
         )
 
         # An empty cc_library to make rule dependency consistent.
-        native.cc_library(
+        cc_library(
             name = name,
             **kargs
         )
@@ -259,7 +259,7 @@
     if use_grpc_plugin:
         cc_libs = cc_libs + ["//external:grpc_lib"]
 
-    native.cc_library(
+    cc_library(
         name = name,
         srcs = gen_srcs,
         hdrs = gen_hdrs,

third_party/protobuf/3.6.1/util/python/BUILD

diff --git a/third_party/protobuf/3.6.1/util/python/BUILD b/third_party/protobuf/3.6.1/util/python/BUILD
index ea9fa64..de47025 100644
--- a/third_party/protobuf/3.6.1/util/python/BUILD
+++ b/third_party/protobuf/3.6.1/util/python/BUILD
@@ -1,3 +1,5 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
 # This is a placeholder for python headers. Projects needing to use
 # fast cpp protos in protobuf's python interface should build with
 # --define=use_fast_cpp_protos=true, and in addition, provide