Add version number to a dedicated bzl file

Adding the version number to defs.bzl caused some problems in our internal codebase.
diff --git a/cc/defs.bzl b/cc/defs.bzl
index dbc9331..8de01bd 100644
--- a/cc/defs.bzl
+++ b/cc/defs.bzl
@@ -19,8 +19,6 @@
 
 _MIGRATION_TAG = "__CC_RULES_MIGRATION_DO_NOT_USE_WILL_BREAK__"
 
-version = "0.0.1"
-
 def _add_tags(attrs):
     if "tags" in attrs and attrs["tags"] != None:
         attrs["tags"] += [_MIGRATION_TAG]
diff --git a/cc/version.bzl b/cc/version.bzl
new file mode 100644
index 0000000..4363594
--- /dev/null
+++ b/cc/version.bzl
@@ -0,0 +1,17 @@
+# Copyright 2019 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Information about the present version of rules_cc."""
+
+version = "0.0.1"
diff --git a/distro/BUILD b/distro/BUILD
index ed14028..1a4b0f6 100644
--- a/distro/BUILD
+++ b/distro/BUILD
@@ -2,7 +2,7 @@
     default_visibility = ["//visibility:private"],
 )
 
-load("@rules_cc//cc:defs.bzl", "version")
+load("@rules_cc//cc:version.bzl", "version")
 load("@rules_pkg//:pkg.bzl", "pkg_tar")
 load("@rules_pkg//releasing:defs.bzl", "print_rel_notes")