sdl2 2.0.0

Note that we still need the SDL2 ports of supporting libraries, e.g.
SDL2_image.

Formula/sdl2.rb

@@ -0,0 +1,39 @@
+require 'formula'
+
+class Sdl2 < Formula
+  homepage 'http://www.libsdl.org/'
+  url 'http://www.libsdl.org/release/SDL2-2.0.0.tar.gz'
+  sha1 'a907eb5203abad6649c1eae0120d96c0a1931350'
+
+  head 'http://hg.libsdl.org/SDL', :branch => 'SDL-2.0', :using => :hg
+
+  if build.head?
+    depends_on :automake
+    depends_on :libtool
+  end
+
+  option :universal
+
+  def install
+    # we have to do this because most build scripts assume that all sdl modules
+    # are installed to the same prefix. Consequently SDL stuff cannot be
+    # keg-only but I doubt that will be needed.
+    inreplace %w[sdl2.pc.in sdl2-config.in], '@prefix@', HOMEBREW_PREFIX
+
+    ENV.universal_binary if build.universal?
+
+    system "./autogen.sh" if build.head?
+
+    args = %W[--prefix=#{prefix}]
+    # LLVM-based compilers choke on the assembly code packaged with SDL.
+    args << '--disable-assembly' if ENV.compiler == :llvm or (ENV.compiler == :clang and MacOS.clang_build_version < 421)
+    args << '--without-x'
+
+    system './configure', *args
+    system "make install"
+  end
+
+  def test
+    system "#{bin}/sdl2-config", "--version"
+  end
+end