[build] Add python_library for markupsafe

Change-Id: Ia068f1922980eb4c861e42c8eccdde4bfdb978af
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/markupsafe/+/511340
Reviewed-by: Shai Barack <shayba@google.com>

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
new file mode 100644
index 0000000..b7fbec8
--- /dev/null
+++ b/BUILD.gn
@@ -0,0 +1,14 @@
+# Copyright 2021 The Fuchsia Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//build/python/python_library.gni")
+
+python_library("markupsafe") {
+  sources = [
+    "__init__.py",
+    "_compat.py",
+    "_constants.py",
+    "_native.py",
+  ]
+}

README.fuchsia

diff --git a/README.fuchsia b/README.fuchsia
index ece1bb7..9394606 100644
--- a/README.fuchsia
+++ b/README.fuchsia
@@ -12,3 +12,4 @@
 Local Modifications:
 Added README.fuchsia.
 Added py_srcs.gni.
+Added BUILD.gn.