Adding BUILD.gn file to build using gn and ninja

Change-Id: Ife3ba2ef131bf89e71c58da6c7cfde6ea87eb16f

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
new file mode 100644
index 0000000..f4bebc9
--- /dev/null
+++ b/BUILD.gn
@@ -0,0 +1,34 @@
+# Copyright 2017 The Roughtime Authors.
+
+# 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.
+
+executable("simple_server") {
+  sources = [
+    "clock_linux.cc",
+    "protocol.cc",
+    "server.cc",
+    "simple_server.cc",
+    "simple_server_main.cc",
+    "sys_time.cc",
+    "udp_processor.cc",
+  ]
+  defines = [
+    "USE_GLOG",
+    "ROUGHTIME_OPEN_SOURCE",
+  ]
+  include_dirs = [ "." ]
+  deps = [
+    "//third_party/boringssl",
+    "//third_party/glog",
+  ]
+}