Switch from Makefile to GN

GN makes it easier for us to have a modular build where we can define
tests and reuse code without having to hack on Makefiles. It also has
tools to analyze the build and comes with extensive documentation.

Change-Id: Ib28bc7b68d429e3c3193784c7a80d05ee35c6295
diff --git a/test.cpp b/test.cpp
new file mode 100644
index 0000000..64f0d09
--- /dev/null
+++ b/test.cpp
@@ -0,0 +1,6 @@
+#include <iostream>
+
+int main(void) {
+  std::cout << "This looks like it worked!" << std::endl;
+  return 0;
+}