Add Go build support for GN.

mojo/go/BUILD.gn

+# Copyright 2014 The Chromium 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/go/rules.gni")
+
+group("go") {
+  deps = [
+    ":system_test",
+  ]
+}
+
+go_test_binary("system_test") {
+#  go_base_module = "mojo"
+  sources = [
+    "tests/system_test.go",
+  ]
+#  deps = [
+#    "//mojo/system",
+#  ]
+#  datadeps = [
+#    "//mojo/public/python:system",

[qsr, 2014/09/18 08:30:38]

Why do you depend on anything python here?

[tburkard, 2014/09/18 14:23:42]

I had copied this from your python template. I wasn't sure how this works here
in go. I know I will have to depend on the other go files. Are these deps or
datadeps (datadeps perhaps because they are not targets that need to be
compiled)? See comment to other question.

+#  ]
+}