stockfish: import from homebrew/games.

Formula/stockfish.rb

@@ -0,0 +1,30 @@
+class Stockfish < Formula
+  desc "Strong open-source chess engine"
+  homepage "http://stockfishchess.org/"
+  url "https://stockfish.s3.amazonaws.com/stockfish-8-src.zip"
+  sha256 "7bad36f21f649ab24f6d7786bbb1b74b3e4037f165f32e3d42d1ae19c8874ce9"
+  head "https://github.com/official-stockfish/Stockfish.git"
+
+  bottle do
+    cellar :any_skip_relocation
+    sha256 "6191999c37070259207340cafcee3876f8e66dc44b903f484d930072ddc7f5bc" => :sierra
+    sha256 "6191999c37070259207340cafcee3876f8e66dc44b903f484d930072ddc7f5bc" => :el_capitan
+    sha256 "5061823dfe7f06672ed5a0b5608e20ea141a8c6f1bf79f5ac5bedcc71ca56ba8" => :yosemite
+  end
+
+  def install
+    if Hardware::CPU.features.include? :popcnt
+      arch = "x86-64-modern"
+    else
+      arch = Hardware::CPU.ppc? ? "ppc" : "x86"
+      arch += "-" + (MacOS.prefer_64_bit? ? "64" : "32")
+    end
+
+    system "make", "-C", "src", "build", "ARCH=#{arch}"
+    bin.install "src/stockfish"
+  end
+
+  test do
+    system "#{bin}/stockfish", "go", "depth", "20"
+  end
+end