systemlibs: unbundle enum34

Signed-off-by: Jason Zaman <jason@perfinion.com>

tensorflow/workspace.bzl

@@ -389,6 +389,7 @@ def tf_repositories(path_prefix = "", tf_repo_name = ""):
         ],
         sha256 = "8ad8c4783bf61ded74527bffb48ed9b54166685e4230386a9ed9b1279e2df5b1",
         build_file = clean_dep("//third_party:enum34.BUILD"),
+        system_build_file = clean_dep("//third_party/systemlibs:enum34.BUILD"),
         strip_prefix = "enum34-1.1.6/enum",
     )
 

third_party/systemlibs/enum34.BUILD

@@ -0,0 +1,14 @@
+# Description:
+#   enum34 provides a backport of the enum module for Python 2.
+
+licenses(["notice"])  # MIT
+
+filegroup(
+    name = "LICENSE",
+    visibility = ["//visibility:public"],
+)
+
+py_library(
+    name = "enum",
+    visibility = ["//visibility:public"],
+)

third_party/systemlibs/syslibs_configure.bzl

@@ -20,6 +20,7 @@ VALID_LIBS = [
     "curl",
     "cython",
     "double_conversion",
+    "enum34_archive",
     "flatbuffers",
     "gast_archive",
     "gif_archive",