New formula: libstxxl 1.3.1

Closes Homebrew/homebrew#8356.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Formula/libstxxl.rb

@@ -0,0 +1,21 @@
+require 'formula'
+
+class Libstxxl < Formula
+  url 'http://sourceforge.net/projects/stxxl/files/stxxl/1.3.1/stxxl-1.3.1.tar.gz'
+  homepage 'http://stxxl.sourceforge.net/'
+  md5 '8d0e8544c4c830cf9ae81c39b092438c'
+
+  def install
+    inreplace "Makefile" do |s|
+      s.change_make_var! "USE_MACOSX", "yes"
+    end
+
+    ENV['COMPILER'] = ENV.cxx
+
+    system "make", "config_gnu"
+    system "make", "library_g++"
+
+    prefix.install Dir['include']
+    prefix.install Dir['lib']
+  end
+end